Having trouble with the converting of strings to doubles. I've tried using strtod, but that does the same thing. It seems like this should work just find but perhaps using strtok has something to do with it. data[i].calories is a double of course.
data[i].calories = atof(strtok(NULL, ","));
It seems to assign either a positive or negative really big number to calories (a double, which means it must be reading the value wrong.
Data Expected:
12cx7,23:55:00,->0.968900025,(this could also be a double),0,74,0,2,
What it instead actually gets:
12cx7,23:55:00,->-537691972,0,0,74,0,2,
EDIT:
IM AN IDIOT I WAS DISPLAYING IT AS AN INT PFFFFFFFFFFFFFFFF.
Assuming we have an input like this,
12cx7,23:55:00,0.968900025,,0,74,0,2,
And we would like to,
"Having trouble with the converting of strings to doubles."
That is we would like to separate the alphanumeric data . And then the remaining ints and floats, we would like to print in the correct format, I would do something like the following:
#include <cstring>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
int isNumeric (const char * s)
{
if (s == NULL || *s == '\0' || isspace(*s)) {
return 0;
}
char * p;
strtod (s, &p);
return *p == '\0';
}
bool isInteger(double val)
{
int truncated = (int)val;
return (val == truncated);
}
int main() {
// If this is your input:
char input[100] = "12cx7,23:55:00,0.968900025,0,74,0,2,";
// Then step 1 -> we split the values
char *token = std::strtok(input, ",");
while (token != NULL) {
// Step 2 -> we check if the values in the string are numeric or otherwise
if (isNumeric(token)) {
// printf("%s\n", token);
char* endptr;
double v = strtod(token, &endptr);
// Step 3 -> we convert the strings containing no fractional parts to ints
if (isInteger(v)) {
int i = strtol(token, &endptr, 10);
printf("%d\n", i);
} else {
// Step 4 -> we print the remaining numeric-strings as floats
printf("%f\n", v);
}
}
else {
// What is not numeric, print as it is, like a string
printf("%s,",token);
}
token = std::strtok(NULL, ",");
}
}
For the isInteger() function, I took the idea/code from this accepted answer. The rest is quite original and probably could be refined/improved.
This produces then this output:
12cx7,23:55:00,0.968900,0,74,0,2,
which is basically the output that we want, except with the very important difference that the input was a whole single string and the output is doubles/floats, ints and strings correctly identified and printed with the correct formatting.
EDIT:
I am not any doing error-handling here. This code is just to give the OP a proof-of-concept. Check and control for any errors returned from the used strtoX functions.
Related
I am trying to make put command line arguments by the user into an array but I am unsure how to approach it.
For example say I ran my program like this.
./program 1,2,3,4,5
How would I store 1 2 3 4 5 without the commas, and allow it to be passed to other functions to be used. I'm sure this has to do with using argv.
PS: NO space-separated, I want the numbers to parse into integers, I have an array of 200, and I want these numbers to be stored in the array as, arr[0] = 1, arr[1] = 2....
store 1 2 3 4 5 without the commas, and allow it to be passed to other functions to be used.
PS: NO space-separated, I want the numbers to parse into integers
Space or comma-separated doesn't matter. Arguments always come in as strings. You will have to do the work to turn them into integers using atoi (Ascii-TO-Integer).
Using spaces between arguments is the normal convention: ./program 1 2 3 4 5. They come in already separated in argv.
Loop through argv (skipping argv[0], the program name) and run them through atoi.
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
for(int i = 1; i < argc; i++) {
int num = atoi(argv[i]);
printf("%d: %d\n", i, num);
}
}
Using commas is going to make that harder. You first have to split the string using the kind of weird strtok (STRing TOKenizer). Then again call atoi on the resulting values.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char *argv[]) {
char *token = strtok(argv[1], ",");
while(token) {
int num = atoi(token);
printf("%d\n", num);
token = strtok(NULL, ",");
}
}
This approach is also more fragile than taking them as individual arguments. If the user types ./program 1, 2, 3, 4, 5 only 1 will be read.
One of the main disadvantages to using atoi() is it provides no check on the string it is processing and will happily accept atoi ("my-cow"); and silently fail returning 0 without any indication of a problem. While a bit more involved, using strtol() allows you to determine what failed, and then recover. This can be as simple or as in-depth a recovery as your design calls for.
As mentioned in the comment, strtol() was designed to work through a string, converting sets of digits found in the string to a numeric value. On each call it will update the endptr parameter to point to the next character in the string after the last digit converted (to each ',' in your case -- or the nul-terminating character at the end). man 3 strtol provides the details.
Since strtol() updates endptr to the character after the last digit converted, you check if nptr == endptr to catch the error when no digits were converted. You check errno for a numeric conversion error such as overflow. Lastly, since the return type is long you need to check if the value returned is within the range of an int before assigning to your int array.
Putting it altogether with a very minimal bit of error handling, you could do something like:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#define NELEM 200 /* if you need a constant, #define one (or more) */
int main (int argc, char **argv) {
int arr[NELEM] = {0}, ndx = 0; /* array and index */
char *nptr = argv[1], *endptr = nptr; /* nptr and endptr */
if (argc < 2) { /* if no argument, handle error */
fputs ("error: no argument provided.\n", stderr);
return 1;
}
else if (argc > 2) { /* warn on more than 2 arguments */
fputs ("warning: more than one argument provided.\n", stdout);
}
while (ndx < NELEM) { /* loop until all ints processed or arr full */
int error = 0; /* flag indicating error occured */
long tmp = 0; /* temp var to hold strtol return */
char *onerr = NULL; /* pointer to next comma after error */
errno = 0; /* reset errno */
tmp = strtol (nptr, &endptr, 0); /* attempt conversion to long */
if (nptr == endptr) { /* no digits converted */
fputs ("error: no digits converted.\n", stderr);
error = 1;
onerr = strchr (endptr, ',');
}
else if (errno) { /* overflow in conversion */
perror ("strtol conversion error");
error = 1;
onerr = strchr (endptr, ',');
}
else if (tmp < INT_MIN || INT_MAX < tmp) { /* check in range of int */
fputs ("error: value outside range of int.\n", stderr);
error = 1;
onerr = strchr (endptr, ',');
}
if (!error) { /* error flag not set */
arr[ndx++] = tmp; /* assign integer to arr, advance index */
}
else if (onerr) { /* found next ',' update endptr to next ',' */
endptr = onerr;
}
else { /* no next ',' after error, break */
break;
}
/* if at end of string - done, break loop */
if (!*endptr) {
break;
}
nptr = endptr + 1; /* update nptr to 1-past ',' */
}
for (int i = 0; i < ndx; i++) { /* output array content */
printf (" %d", arr[i]);
}
putchar ('\n'); /* tidy up with newline */
}
Example Use/Output
This will handle your normal case, e.g.
$ ./bin/argv1csvints 1,2,3,4,5
1 2 3 4 5
It will warn on bad arguments in list while saving all good arguments in your array:
$ ./bin/argv1csvints 1,my-cow,3,my-cat,5
error: no digits converted.
error: no digits converted.
1 3 5
As well as handling completely bad input:
$ ./bin/argv1csvints my-cow
error: no digits converted.
Or no argument at all:
$ ./bin/argv1csvints
error: no argument provided.
Or more than the expected 1 argument:
$ ./bin/argv1csvints 1,2,3,4,5 6,7,8
warning: more than one argument provided.
1 2 3 4 5
The point to be made it that with a little extra code, you can make your argument parsing routine as robust as need be. While your use of a single argument with comma-separated values is unusual, it is doable. Either manually tokenizing (splitting) the number on the commas with strtok() (or strchr() or combination of strspn() and strcspn()), looping with sscanf() using something similar to the "%d%n" format string to get a minimal succeed / fail indication with the offset of the next number from the last, or using strtol() and taking advantage of its error reporting. It's up to you.
Look things over and let me know if you have questions.
This is how I'd deal with your requirement using strtol(). This does not damage the input string, unlike solutions using strtok(). It also handles overflows and underflows correctly, unlike solutions using atoi() or its relatives. The code assumes you want to store an array of type long; if you want to use int, you can add testing to see if the value converted is larger than INT_MAX or less than INT_MIN and report an appropriate error if it is not a valid int value.
Note that handling errors from strtol() is a tricky business, not least because every return value (from LONG_MIN up to LONG_MAX) is also a valid result. See also Correct usage of strtol(). This code requires no spaces before the comma; it permits them after the comma (so you could run ./csa43 '1, 2, -3, 4, 5' and it would work). It does not allow spaces before commas. It allows leading spaces, but not trailing spaces. These issues could be fixed with more work — probably mostly in the read_value() function. It may be that the validation work in the main loop should be delegated to the read_value() function — it would give a better separation of duty. OTOH, what's here works within limits. It would be feasible to allow trailing spaces, or spaces before commas, if that's what you choose. It would be equally feasible to prohibit leading spaces and spaces after commas, if that's what you choose.
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
static int read_val(const char *str, char **eov, long *value)
{
errno = 0;
char *eon;
if (*str == '\0')
return -1;
long val = strtol(str, &eon, 0);
if (eon == str || (*eon != '\0' && *eon != ',') ||
((val == LONG_MIN || val == LONG_MAX) && errno == ERANGE))
{
fprintf(stderr, "Could not convert '%s' to an integer "
"(the leftover string is '%s')\n", str, eon);
return -1;
}
*value = val;
*eov = eon;
return 0;
}
int main(int argc, char **argv)
{
if (argc != 2)
{
fprintf(stderr, "Usage: %s n1,n2,n3,...\n", argv[0]);
exit(EXIT_FAILURE);
}
enum { NUM_ARRAY = 200 };
long array[NUM_ARRAY];
size_t nvals = 0;
char *str = argv[1];
char *eon;
long val;
while (read_val(str, &eon, &val) == 0 && nvals < NUM_ARRAY)
{
array[nvals++] = val;
str = eon;
if (str[0] == ',' && str[1] == '\0')
{
fprintf(stderr, "%s: trailing comma in number string\n", argv[1]);
exit(EXIT_FAILURE);
}
else if (str[0] == ',')
str++;
}
for (size_t i = 0; i < nvals; i++)
printf("[%zu] = %ld\n", i, array[i]);
return 0;
}
Output (program csa43 compiled from csa43.c):
$ csa43 1,2,3,4,5
[0] = 1
[1] = 2
[2] = 3
[3] = 4
[4] = 5
$
Hi folks thanks in advance for any help, I'm doing the CS50 course i'm at the very beginning of programming.
I'm trying to check if the string from the main function parameter string argv[] is indeed a number, I searched multiple ways.
I found in another topic How can I check if a string has special characters in C++ effectively?, on the solution posted by the user Jerry Coffin:
char junk;
if (sscanf(str, "%*[A-Za-z0-9_]%c", &junk))
/* it has at least one "special" character
else
/* no special characters */
if seems to me it may work for what I'm trying to do, I'm not familiar with the sscanf function, I'm having a hard time, to integrate and adapt to my code, I came this far I can't understand the logic of my mistake:
#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
int numCheck(string[]);
int main(int argc, string argv[]) {
//Function to check for user "cooperation"
int key = numCheck(argv);
}
int numCheck(string input[]) {
int i = 0;
char junk;
bool usrCooperation = true;
//check for user "cooperation" check that key isn't a letter or special sign
while (input[i] != NULL) {
if (sscanf(*input, "%*[A-Za-z_]%c", &junk)) {
printf("test fail");
usrCooperation = false;
} else {
printf("test pass");
}
i++;
}
return 0;
}
check if the string from the main function parameter string argv[] is indeed a number
A direct way to test if the string converts to an int is to use strtol(). This nicely handles "123", "-123", "+123", "1234567890123", "x", "123x", "".
int numCheck(const char *s) {
char *endptr;
errno = 0; // Clear error indicator
long num = strtol(s, &endptr, 0);
if (s == endptr) return 0; // no conversion
if (*endptr) return 0; // Junk after the number
if (errno) return 0; // Overflow
if (num > INT_MAX || num < INT_MIN) return 0; // int Overflow
return 1; // Success
}
int main(int argc, string argv[]) {
// Call each arg[] starting with `argv[1]`
for (int a = 1; a < argc; a++) {
int success = numCheck(argv[a]);
printf("test %s\n", success ? "pass" : "fail");
}
}
sscanf(*input, "%*[A-Za-z_]%c", &junk) is the wrong approach for testing numerical conversion.
You pass argv to numcheck and test all strings in it: this is incorrect as argv[0] is the name of the running executable, so you should skip this argument. Note also that you should pass input[i] to sscanf(), not *input.
Furthermore, lets analyze the return value of sscanf(input[i], "%*[A-Za-z_]%c", &junk):
it returns EOF if the input string is empty,
it returns 0 if %*[A-Za-z_] fails,
it also returns 0 if the conversion %c fails after the %*[A-Za-z_] succeeds,
it returns 1 is both conversions succeed.
This test is insufficient to check for non digits in the string, it does not actually give useful information: the return value will be 0 for the string "1" and also for the string "a"...
sscanf() is very tricky, full of quirks and traps. Definitely not the right tool for pattern matching.
If the goal is to check that the strings contain only digits (at least one), use this instead, using the often overlooked standard function strspn():
#include <stdio.h>
#include <string.h>
int numCheck(char *input[]) {
int i;
int usrCooperation = 1;
//check for user "cooperation" check that key isn't a letter or special sign
for (i = 1; input[i] != NULL; i++) {
// count the number of matching character at the beginning of the string
int ndigits = strspn(input[i], "0123456789");
// check for at least 1 digit and no characters after the digits
if (ndigits > 0 && input[i][ndigits] == '\0') {
printf("test passes: %d digits\n", ndigits);
} else {
printf("test fails\n");
usrCooperation = 0;
}
}
return usrCooperation;
}
Let's try this again:
This is still your problem:
if (sscanf(*input, "%*[A-Za-z_]%c", &junk))
but not for the reason I originally said - *input is equal to input[0]. What you want to have there is
if ( sscanf( input[i], "%*[A-Za-z_]%c", &junk ) )
what you're doing is cycling through all your command line arguments in the while loop:
while( input[i] != NULL )
but you're only actually testing input[0].
So, quick primer on sscanf:
The first argument (input) is the string you're scanning. The type of this argument needs to be char * (pointer to char). The string typedef name is an alias for char *. CS50 tries to paper over the grosser parts of C string handling and I/O and the string typedef is part of that, but it's unique to the CS50 course and not a part of the language. Beware.
The second argument is the format string. %[ and %c are format specifiers and tell sscanf what you're looking for in the string. %[ specifies a set of characters called a scanset - %[A-Za-z_] means "match any sequence of upper- and lowercase letters and underscores". The * in %*[A-Za-z_] means don't assign the result of the scan to an argument. %c matches any character.
Remaining arguments are the input items you want to store, and their type must match up with the format specifier. %[ expects its corresponding argument to have type char * and be the address of an array into which the input will be stored. %c expects its corresponding argument (in this case junk) to also have type char *, but it's expecting the address of a single char object.
sscanf returns the number of items successfully read and assigned - in this case, you're expecting the return value to be either 0 or 1 (because only junk gets assigned to).
Putting it all together,
sscanf( input, "%*[A-Za-z_]%c", &junk )
will read and discard characters from input up until it either sees the string terminator or a character that is not part of the scanset. If it sees a character that is not part of the scanset (such as a digit), that character gets written to junk and sscanf returns 1, which in this context is treated as "true". If it doesn't see any characters outside of the scanset, then nothing gets written to junk and sscanf returns 0, which is treated as "false".
EDIT
So, chqrlie pointed out a big error of mine - this test won't work as intended.
If there are no non-letter and non-underscore characters in input[i], then nothing gets assigned to junk and sscanf returns 0 (nothing assigned). If input[i] starts with a letter or underscore but contains a non-letter or non-underscore character later on, that bad character will be converted and assigned to junk and sscanf will return 1.
So far so good, that's what you want to happen. But...
If input[i] starts with a non-letter or non-underscore character, then you have a matching failure and sscanf bails out, returning 0. So it will erroneously match a bad input.
Frankly, this is not a very good way to test for the presence of "bad" characters.
A potentially better way would be to use something like this:
while ( input[i] )
{
bool good = true;
/**
* Cycle through each character in input[i] and
* check to see if it's a letter or an underscore;
* if it isn't, we set good to false and break out of
* the loop.
*/
for ( char *c = input[i]; *c; c++ )
{
if ( !isalpha( *c ) && *c != '_' )
{
good = false;
break;
}
}
if ( !good )
{
puts( "test fails" );
usrCooperation = 0;
}
else
{
puts( "test passes" );
}
}
I followed the solution by the user "chux - Reinstate Monica". thaks everybody for helping me solve this problem. Here is my final program, maybe it can help another learner in the future. I decided to avoid using the non standard library "cs50.h".
//#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <limits.h>
void keyCheck(int);
int numCheck(char*);
int main(int argc, char* argv[])
{
//Error code == 1;
int key = 0;
keyCheck(argc); //check that two parameters where sent to main.
key = numCheck(argv[1]); //Check for user "cooperation".
return 0;
}
//check for that main received two parameters.
void keyCheck(int key)
{
if (key != 2) //check that main argc only has two parameter. if not terminate program.
{
exit(1);
}
}
//check that the key (main parameter (argv [])) is a valid number.
int numCheck(char* input)
{
char* endptr;
errno = 0;
long num = strtol(input, &endptr, 0);
if (input == endptr) //no conversion is possible.
{
printf("Error: No conversion possible");
return 1;
}
else if (errno == ERANGE) //Input out of range
{
printf("Error: Input out of range");
return 1;
}
else if (*endptr) //Junk after numeric text
{
printf("Error: data after main parameter");
return 1;
}
else //conversion succesfull
{
//verify that the long int is in the integer limits.
if (num >= INT_MIN && num <= INT_MAX)
{
return num;
}
//if the main parameter is bigger than an int, terminate program
else
{
printf("Error key out of integer limits");
exit(1);
}
}
/* else
{
printf("Success: %ld", num);
return num;
} */
}
I'm trying to write a C program that only prints the last occurrence of repeating letters of a string. I have that part done but I want to store all those chars in a string. What I have so far is:
#include <stdio.h>
#include <ctype.h>
#include <stdbool.h>
bool isLast(char *arg1, char ch, int p) {
p++;
while (arg1[p] != '\0') {
if ((arg1[p]) == ch) {
return false;
}
p++;
}
return true;
}
int main() {
char *word = "kaax";
char *vals = "1235";
char *result = "";
for (int i = 0; word[i] != '\0'; i++) {
if (isLast(word, word[i], i)) {
result += vals[i];
}
}
printf("%s", result);
}
I want:
printf("%s",result);
to print:
fxkav
Since that is the logical result of my program and what the output should be.
How to phrase it ... Not at all.
Your "empty string" is a string literal of size 1 (containing only '\0'. It cannot be changed and even lesss extended.
If you need to manipulate "strings" (which in C is not really an existing concept) you need to represent them as sequences of characters, which are stored in a data structure which allows to change the contained characters and, in your case, also has space for more characters.
In cases where you can determine a maximum size (MAXSIZE) you could define an array of characters of that size like this
char SizedCharArray[MAXSIZE];
I have dynamic string like: "/users/5/10/fnvfnvdjvndfvjvdklchsh" and also dynamic format like "/users/%u/%d/%s", how to check these strings matches?
As string i mean char[255] or char* str = malloc(x).
I tried use sscanf but i dont know number of arguments and types, if i do:
int res = sscanf(input, format);
I have stack overflow, or can i allocate stack to prevent this?
Example like this:
void* buffer = malloc(1024);
int res = sscanf(input, format, buffer);
I would like have function like this:
bool stringMatches(const char* format, const char* input);
stringMatches("/users/%u/%d/%s", "/users/5/10/fnvfnvdjvndfvjvdklchsh"); //true
stringMatches("/users/%u/%d/%s", "/users/5/10"); //false
stringMatches("/users/%u/%d/%s", "/users/-10/10/aaa"); //false %u is unsigned
Do you see any solution?
Thanks in advance.
I don't think that there is a scanf-like matching function in the standard lib, so you will have to write your own. Replicating all details of the scanf behaviour is difficult, but it's probably not necessary.
If you allow only % and a limited selection of single format identifiers without size, width and precision information, the code isn't terribly complex:
bool stringMatches(const char *format, const char *input)
{
while (*format) {
if (*format == '%') {
format++;
switch(*format++) {
case '%': {
if (*input++ != '%') return false;
}
break;
case 'u':
if (*input == '-') return false;
// continue with 'd' case
case 'd': {
char *end;
strtol(input, &end, 0);
if (end == input) return false;
input = end;
}
break;
case 's': {
if (isspace((uint8_t) *input)) return false;
while (*input && !isspace((uint8_t) *input)) input++;
}
break;
default:
return false;
}
} else {
if (*format++ != *input++) return false;
}
}
return (*input == '\0');
}
Some notes:
I've parsed the numbers with strtol. If you want to include floating-point number formats, you could use strtod for that, if your embedded system provides it. (You could also parse stretches of isdigit() chars as valid numbers.)
The 'u' case falls through to the 'd' case here. The function strtoul parses an unsigned long, but it allows a minus sign, so that case is caught explicitly. (But the way it is caught, it won't allow leading white space.)
You could implement your own formats or re-interpret existing ones. For example you could decide that you don't want leading white space for numbers or that a string ends with a slash.
It's a rather tricky one. I don't think C has very useful built in functions that will help you.
What you could do is using a regex. Something like this:
#include <sys/types.h>
#include <regex.h>
#include <stdio.h>
int main(void)
{
regex_t regex;
if (regcomp(®ex, "/users/[[:digit:]]+", 0)) {
fprintf("Error\n");
exit(1);
}
char *mystring = "/users/5/10/fnvfnvdjvndfvjvdklchsh";
if( regexec(®ex, myString, 0, NULL, 0) == 0)
printf("Match\n");
}
The regex in the code above does not suit your example. I just used something to show the idea. I think it would correspond to the format string "/users/%u" but I'm not sure. Nevertheless, I think this is one of the easiest ways to tackle this problem.
The easiest is to just try parsing it with sscanf, and see if the scan succeeded.
char * str = "/users/5/10/fnvfnvdjvndfvjvdklchsh";
unsigned int tmp_u;
int tmp_d;
char tmp_s[256];
int n = sscanf (str, "/users/%u/%d/%s", &tmp_u, &tmp_d, tmp_s);
if (n!=3)
{
/* Match failed */
}
Just remember that you don't have to mach everything in one go. You can use the %n format specifier to get the number of bytes parsed, and increment the string for the next parse.
This example abuses the fact that bytes_parsed will not be modified if the parsing doesn't reach the %n specifier:
char * str = "/users/5/10/fnvfnvdjvndfvjvdklchsh";
int bytes_parsed = 0;
/* parse prefix */
sscanf("/users/%n", &bytes_parsed);
if (bytes_parsed == 0)
{
/* Parse error */
}
str += bytes_parsed; /* str = "5/10/fnvfnvdjvndfvjvdklchsh"; */
bytes_parsed = 0;
/* Parse next num */
unsigned int tmp_u
sscanf(str, "%u%n", &tmp_u, &bytes_parsed);
if (bytes_parsed)
{
/* Number was an unsigned, do something */
}
else
{
/* First number was not an `unsigned`, so we try parsing it as signed */
unsigned int tmp_d
sscanf(str, "%d%n", &tmp_d, &bytes_parsed);
if (bytes_parsed)
{
/* Number was an unsigned, do something */
}
}
if (!bytes_parsed)
{
/* failed parsing number */
}
str += bytes_parsed; /* str = "/10/fnvfnvdjvndfvjvdklchsh"; */
......
Let's say I've got the file
5f2
3f6
2f1
And the code:(The printf should print the second numbers (i.e 2,6, and 1) but it doesn't
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
int main (int argc, char * argv[])
{
FILE *ptr;
char str[100];
char * token;
int a, b, i;
int arr[4];
if(argc > 1)
{
ptr = fopen(argv[1],"r");
if(ptr == NULL)
{
exit(1);
}
}
else
{
exit(1);
}
//And I'm looking to parse the numbers between the "f" so..
while(fgets(str,100,ptr) != NULL)
{
token = strstr(str,"f");
if(token != NULL)
{
a = atol(str); // first number
b = atol(token+1); // second number
arr[i] = b; // store each b value (3 of em) into this array
}
i++;
printf("Values are %d\n",arr[i]); //should print 2,6 and 1
}
}
I've tried to move the printf outside the loop, but that seems to print an even weirder result, I've seen posts about storing integers from a file into an array before, however since this involves using strstr, I'm not exactly sure the procedure is the same.
int i,j=0;
while(fgets(str,sizeof(str),file) != NULL)
{
size_t n = strlen(str);
if(n>0 && str[n-1] == '\n')
str[n-1] = '\0';
i = str[strlen(str)-1] - '0'; /* Convert the character to int */
printf("%d\n",i);// Or save it to your int array arr[j++] = i;
}
Just move to the last character as shown and print it out as integer.
PS: fgets() comes with a newline character you need to suppress it as shown
You are never initializing i, then you are reading into arr[i] (which just happens to not crash right there), then increment i (to "undefined value + 1"), then print arr[i] -- i.e., you are writing to and reading from uninitialized memory.
Besides, your FILE * is ptr, not file. And you should get into the habit of using strtol() instead of atol(), because the former allows you to properly check for success (and recover from error).