I have written a function that is supposed to read the number of sentences in a .txt file, but when the function is called and done, it gives me a value of 0.
This program over all has 3 more functions to figure out different properties of the file and I have them working great. This one is laid out the same way I wrote my other functions just looking for some advice on why I am getting 0 as my number of sentences.
void ptrCntS (FILE* sp1, int sCount)
{
char sentence = 'O';
int myChr;
if (!(sp1 = fopen("Hello.txt", "r")))
{
printf("error opening Hello.txt");
return(1);
}
while ((myChr = fgetc(sp1)) != EOF)
{
if ('.')
{
sentence ='O';
}
else if (sentence == 'O')
{
sCount++;
sentence = 'I';
}
}
fclose(sp1);
printf ("Total number of sentences are:\t%d", sCount);
return;
}
instead of return use return(sCount);
and assign the return value to some int variable in calling function
like
int sentCount;
.
.
.
sentCount=ptrCntS (param1,param2);
if ('.') is always true, thus else... code never reached. Use if( myChr == '.' ) instead.
Function compiles now and runs properly. This function is being called from a switch in a previous function where I had my addresses set and included my print statement for the totals so that I would not have to write another function in the end to call on all my counts and print their results. Instead I set my case 'A': to call all of my counting functions(in this case that is what the original code is) and than display my results. I am sorry for any lengthiness or my hard to understand writing I am new to the C language and I am having a hard time grasping the literature but making some process on understanding the syntax.
Related
I'm pretty new to coding and especially to C, so I decided to take the CS50 course as an introduction to the language. I just finished watching the first lecture on C and, as a means to test my knowledge on the subject, I attempted to write a short little program. Also I am using the course's library for the get_int() function.
The goal is to test the user's input and check if it's less or equal to ten. If it matches the parameters, the program should print the "Success!" message and exit; otherwise, it should ask for input again. If the input value is over 10, the program responds just as expected, but if you input a value of 10 or less, it ends up asking you for input one more time before actually exiting. I think it's probably something with the "for" loop, but I just can't figure it out.
My code:
#include <stdio.h>
#include <cs50.h>
#include <stdlib.h>
int check_for_value();
int main()
{
for(check_for_value(); check_for_value() != 1; check_for_value())
{
printf("Failed!\n");
}
exit(0);
}
int check_for_value()
{
int i = get_int("Your value: \n");
if(i <= 10)
{
printf("Success!\n");
return 1;
}
else
{
printf("Try again!\n");
return 0;
}
}
That isn't doing exactly what you think it is. In your for loop, each time you write check_for_value(), it is going to call that function. So it will call it the first time and the return value will not matter. It will call it again for the middle statement and then the value will matter because you are comparing the output to not equal to 1. And then again it will call the function in the third statement, where again it won't matter. Usually for something like this, you would use a while loop instead. An example below:
int ret = check_for_value();
while(ret != 1) {
printf("Failed\n");
ret = check_for_value();
}
printf("Success\n");
Technically a for loop can work too as the following:
for(int ret = check_for_value(); ret != 1; ret = check_for_value()) {
printf("Failed\n");
}
The for loop can look very simply
for ( ; !check_for_value(); )
{
printf("Failed!\n");
}
In such a case it is better to use the while loop
while ( !check_for_value() )
{
printf("Failed!\n");
}
As for your for loop
for(check_for_value(); check_for_value() != 1; check_for_value())
^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^
then the underlined calls of the function are not tested.
Also bear in mind that such a definition of a for loop
for(int ret = check_for_value(); ret != 1; ret = check_for_value()) {
printf("Failed\n");
}
is a very bad style of programming. There is redundant records of the function calls. The intermediate variable ret is not used in the body of the loop. So its declaration is also redundant. Never use such a style of programming.
Pay attention to that according to the C Standard the function main without parameters shall be declared like
int main( void )
and the statement
exit( 0 );
is redundant.
We need to create a binary tree which contains content of textfiles. The pointer selection_a and selection_b pointing to another textfile in the directory.
The structure of the textfiles is following:
line: Title
line: OptionA
line: OptionB
line: Text.
The first file is given as parameter while starting the program. All files should be saved at the beginning of the program. Then the text of the first file shows, and the user can input A or B to continue. Based on the selection, the text of File Option A/B is shown and the user can decide again.
The last file of a tree contains no Options: lines 2 and 3 are "-\n".
The problem is, this code only reads all the option A files of the first tree. It doesn't read in any B-Options. In the end, the program shows a memory access error.
I think the problem is that the readingRows function has no abort condition.
current->selection_a = readingRows(input_selection_a);
current->selection_b = readingRows(input_selection_b);
I know the code may be kind of chaotic, but we are beginners in programming. Hope anybody can help us to write an abort-condition.
The function should be aborted if the content of option A (line 3) is "-\n".
Here is the whole function:
struct story_file* readingRows(FILE *current_file)
{
char *buffer = fileSize(current_file);
char *delimiter = "\n";
char *lines = strtok(buffer, delimiter);
int line_counter = 0;
struct story_file *current = malloc(sizeof(struct story_file));
while(lines != NULL)
{
if(line_counter == 0)
{
current->title = lines;
}
else if(line_counter == 1)
{
char *filename_chapter_a = lines;
FILE *input_selection_a = fopen(filename_chapter_a, "r");
if(input_selection_a)
{
current->selection_a = readingRows(input_selection_a);
}
fclose(input_selection_a);
}
else if(line_counter == 2)
{
char *filename_chapter_b = lines;
FILE *input_selection_b = fopen(filename_chapter_b, "r");
if(input_selection_b)
{
current->selection_b = readingRows(input_selection_b);
}
fclose(input_selection_b);
}
else if (line_counter >= 3)
{
current->text = lines;
}
lines = strtok(NULL, delimiter);
line_counter++;
}
return current;
}
There are two items that define a terminating recursive function:
One or more base cases
Recursive calls that move toward a base case
Your code has one base case: while (lines!=NULL) {} return current;, it breaks the while loop when lines is NULL and returns current. In other words, within any particular call to your function, it only terminates when it reaches the end of a file.
Your code moves toward that base case as long as your files do not refer to each other in a loop. We know this because you always read a line, take an action according to your if-else block, and the read the next line. So you always move toward the end of each file you read.
But as you note, the issue is that you don't have a case to handle "no Options", being when lines 2 or 3 are "-\n". So right now, even though you move through files, you are always opening files in line 2. Unless a file is malformed and does not contain a line 2, your recursive call tree never ends. So you just need to add another base case that looks at whether the beginning of lines matches "-\n", and if it does, return before the recursive call. This will end that branch of your recursive tree.
Inside of your while loop, you will need code along the lines of:
if `line_counter` is `2` or `3`
if `lines` starts with your terminating sequence "-\n"
return current
else
`fopen` and make the recursive call
In the parent function that made the recursive call, it will move to the next line and continue as expected.
P.S. Make sure you use free for each malloc you do.
I have a work to do in which I have to keep a loop inside the function expecting the following parameters:
-"i" to insert
-"s" to search
-"q" to quit
How do I keep this loop? I've looked up some options and it seems to be possible using a while or a switch, but I am not sure which is the best way to read those chars (with a fscanf perhaps?). I am also not sure how to read the things after the parameter "i" as the input would be "i word 9", so after detecting the i to insert I have to read a string and an int.
Anyone has any idea how to do this? I am sorry is this seems simple, but I am new to programming.
edit: Here is what I have so far
while (loop) {
fscanf(stdin,"%c",&par);
if (strcmp(&par,"i")){
scanf("%s %d",palavra,p);
raiz = insere(raiz,&palavra,p);
}
else if (strcmp(&par,"b")){
scanf("%s",palavra);
busca(raiz,&palavra);
}
else if (strcmp(&par,"q"))
loop = 0;
}
edit 2: This is what I have now, I am having problems reading the string and integer when the parameter is i, somehow it crashes the function
while (1) {
c = getchar();
if (c == 'f')
break;
else if (c == 'i'){
fscanf(stdin,"%s",&palavra);
scanf("%d",&p);
raiz = insere(raiz,palavra,p);
}
else if (c == 'b') {
scanf("%s",palavra);
busca(raiz,palavra);
}
}
Thanks in advance!
The code you have doesn't look too bad compared to what I believe you want. You can replace the "while (loop)" with "while (1)" and then your exist code "loop = 0;" with "break;" which is a bit more standard way of doing things. Also "fscanf(stdin..." is the same as "scanf(..." ... scanf will read from stdin by default. You might want to check the docs for strcmp because it returns 0 for an exact match and I don't think that will do what you want in your 'if' statements. You should be able to use scanf to read in the values you want, is it giving you an error?
You are using 3 separated scans. That means you can't input this "i word 9", but input one command or parameter at the time separated by EOL(pressing enter).. i, enter, word, enter, 9, enter ... Then the function should actually get further in those "if"s. With those scans you also should consider printing information about expected inputs ("Choose action q/i/f")
And I would recommend using something to test those inputs.
if (scanf("%d", &p) == 0) {
printf("Wrong input");
break;
}
I'm completely new to C and I'm working on a program which has to read in 3 lines from a text file(two numbers and a mathematical symbol) and write out the result. So for example:
The text file looks like:
1
4
*
and my program should be able to read the 3 lines and write out something like "1*4 = 4" or something.
I managed to get to a point where i can read the 3 lines in and show them on screen, so I thought I should put the two numbers in one array and the symbol in another one. The problem is, that I tried to see if the arrays contain the numbers I put in them and my output has some huge numbers in it and I'm not sure why.
Here's the code i wrote:
#include <stdio.h>
#include <io.h>
#include <string.h>
int main(void)
{
int res = 1; /*Creates an integer to hold the result of the check for the file*/
const char *file = "input.txt"; /*String holding the name of the file with the input data*/
res = access(file,R_OK); /*Checks if the file "input.txt" exists*/
if(res == -1)
{ /*IF the file doesn't exist:*/
FILE *input = fopen("input.txt","w"); /*This creates a file called "input.txt" in the directory of the program*/
char write[] = "1\n1\n+"; /*This variable holds the string that's to be written to the file*/
fprintf(input,"%s",write); /*This writes the variable "write" to the file*/
printf("input.txt file created!"); /*Tells you the file is created*/
fclose(input); /*Closes the file after it's done*/
}
else
{ /*IF the file exists:*/
FILE *f = fopen("input.txt","r");
//char line[ 5000 ];
//while ( fgets ( line, sizeof line, f ) != NULL )
//{
// fputs ( line, stdout );
//}
char line[5000];
char nums[2];
char symbol[1];
int i = 0;
while(fgets(line,sizeof line,f)!=NULL)
{
i++;
if(i < 3)
{
fputs(nums,f);
}
else
{
fputs(symbol,f);
}
printf("%d,%d",nums,symbol);
}
printf("\n\n\n");
scanf("\n");
}
return 0;
}
Any help would be greatly appreciated!
Thank you in advance
If you require any more information i will provide it.
This is a self-explanatory algorithm. Also, here is the code that does the operation you are looking for. Generally, the complex operations are accomplished using stack, push and pop method. Once the operators are pushed. One need to apply the BODMAS rule,to evaluate the expression. Since the problem given to you is simple, a simple expression evaluation. This can be simply achieved by FIFO. Here is the algorithm, general explanation. Afterwards, the code is present. This code is well tested.You can extend it to do operations like +,-,division /, %, etc. If you like my answer please appreciate.
#include "stdio.h"
int main(int argc, char *argv[])
{
FILE *fp_op;
int buff[2]; /** assuming a simple operation, thus the buffer size is 3 only, the last one is to store the NULL **/
char operat_buff[2]; /** assuming this operation we can extend it to evaluate an expression **/
fp_op = fopen("calc.txt","rb");
if ( fp_op == 0 )
{
perror("The file doesn't exist to calculate\r\n");
goto error;
}
/** Read the two numbers here **/
fscanf(fp_op,"%d",&(buff[0]));
printf("The buff[1] = %d\r\n",buff[0]);
fscanf(fp_op,"%d",&(buff[1]));
printf("The buff[1] = %d\r\n",buff[1]);
/** read the next line now \n **/
operat_buff[0] = fgetc(fp_op);
/** read the actual character now **/
operat_buff[0] = fgetc(fp_op);
printf("The operat_buff[0] = %d\r\n",operat_buff[0]);
/** Read operation completed **/
/** use switch here **/
switch(operat_buff[0])
{
case '*':
printf("The multiplication result=%d\r\n",buff[0]*buff[1]);
break;
case '+':
printf("The Addition result=%d\r\n",buff[0]+buff[1]);
break;
default:
printf("Add more operations\r\n");
}
return 0;
error:
return -1;
}
I assume that the calc.txt was something like this.
calc.txt
3
5
*
Note: This code is compiled and verified.It compiles with zero warnings. It does the error checking too. You can directly copy and paste it.
What are you reading from the files are simply characters codes: the program has no way of figuring by itself that the character "4" corresponds to the integer number 4. The %d placeholder of printf expects int variables, or it won't work.
If you want just to print the characters you have to save them in char variables (or a char array) and use the placeholder %c in printf. If you want to actually use the numbers and symbols in your program you have more work to do.
Not only in C, but I think in most languages you have to "parse" the characters to numbers.
In C you can use the functions atoi or atol (you have to #include <stdlib.h>) in order to do this conversion.
In order to parse the symbol I'm afraid you will have to use an if or a switch to read the character and perform the operation accordingly.
For example your loop could look like:
while(fgets(line,sizeof line,f)!=NULL)
{
int op1;
int op2;
int res;
char symbol;
i++;
switch (i) {
case 1:
//First line is first operand
op1 = atoi(line);
printf("op1 %d\n",op1);
break;
case 3:
//Second line is second operand
op2 = atoi(line);
printf("op2 %d\n",op2);
break;
//Fifth line is the operator, could be +,-,%./ or anything
case 5:
symbol = line[0];
printf("operand %c\n",symbol);
switch(symbol) {
case '+':
res = op1+op2;
break;
case '-':
res = op1-op2;
break;
default:
//operation not defined, return
return;
}
printf("%d%c%d = %d",op1,symbol,op2,res);
}
}
printf("%d,%d",nums,symbol);
In your code nums and symbol are strings, you can't print them with %d. What you are getting are the addresses of the nums and symbol arrays, respectively - even if that's not the right way of printing an address.
You'll likely want to convert them to integers, using strtol or sscanf and then use those to perform the computation.
I am having a problem with a segmentation fault working in C, and I cannot figure out why this is occurring. I think it has something to do with misuse of the fget(c) function.
while((ch = fgetc(fp))!= EOF) {
printf("Got inside first while: character is currently %c \n",ch); //**********DELETE
while(ch != '\n') {
char word[16]; //Clear out word before beginning
i = i+1; //Keeps track of the current run thru of the loop so we know what input we're looking at.
while(ch != ' ') {
printf("%c ",ch); //**********DELETE
//The following block builds up a character array from the current "word" (separated by spaces) in the input file.
int len = strlen(word);
word[len] = ch;
word[len+1] = '\0';
printf("%s",word);
ch = fgetc(fp);
}
//The following if-else block sets the variables TextA, TextB, and TextC to the appropriate Supply Types from the input.
//This part may be confusing to read mentally, but not to trace. All it does is logically set TextA, B, and C to the 3 different possible values SupplyType.
if(word!=TextB && word!=TextC && i==1 && TextB!="") {
strcpy(TextA,word);
}
else if(word!=TextA && word!=TextC && i==1 && TextC!="") {
strcpy(TextB,word);
}
else if(word!=TextB && word!=TextA && i==1) {
strcpy(TextC,word);
}
switch(i) {
case 1:
if(TextA == word) {
SubTypeOption = 1;
}
else if(TextB == word) {
SubTypeOption = 2;
}
else if(TextC == word) {
SubTypeOption = 3;
}
break;
case 2:
//We actually ultimately don't need to keep track of the product's name, so we do nothing for case i=2. Included for readibility.
break;
case 3:
WholesalePrice = atof(word);
break;
case 4:
WholesaleAmount = atoi(word);
break;
case 5:
RetailPrice = atof(word);
break;
case 6:
RetailAmount = atoi(word);
break;
}//End switch(i)
ch = fgetc(fp);
}//End while(ch != '\n')
//The following if-else block "tallys up" the total amounts of SubTypes bought and sold by the owner.
if(SubTypeOption == 1) {
SubType1OwnersCost = SubType1OwnersCost + (WholesalePrice*(float)WholesaleAmount);
SubType1ConsumersCost = SubType1ConsumersCost + (RetailPrice *(float)RetailAmount);
}
else if(SubTypeOption == 2) {
SubType2OwnersCost = SubType2OwnersCost + (WholesalePrice*(float)WholesaleAmount);
SubType2ConsumersCost = SubType2ConsumersCost + (RetailPrice *(float)RetailAmount);
}
else if(SubTypeOption == 3) {
SubType3OwnersCost = SubType3OwnersCost + (WholesalePrice*(float)WholesaleAmount);
SubType3ConsumersCost = SubType3ConsumersCost + (RetailPrice *(float)RetailAmount);
}
}//End while((ch = fgetc(fp))!= EOF)
Using gdb (just a simple run of the a.out) I found that the problem is related to getc, but it does not tell which line/which one. However, my program does output "Got in side the first while: character is currently S". This S is the first letter in my input file, so I know it is working somewhat how it should, but then causes a seg fault.
Does anyone have any advice on what could be going wrong, or how to debug this problem? I am relatively new to C and confused mostly on syntax. I have a feeling I've done some small syntactical thing wrong.
By the way, this snippet of the code is meant to get a word from a string. Example:
Help me with this program please
should give word equaling "Help"
Update: Now guys I am getting kind of a cool error (although cryptic). When I recompiled I got something like this:
word is now w S
word is now w Su
word is now w Sup
... etc except it goes on for a while, building a pyramid of word.
with my input file having only the string "SupplyTypeA 1.23 1 1.65 1" in it.
UPDATE: Segmentation fault was fixed (the issue was, I was going past the end of the file using fgetc() ). Thanks everyone.
If anyone still glances at this, could they help me figure out why my output file does not contain any of the correct numbers it should? I think I am probably misusing atof and atoi on the words I'm getting.
Make sure you compile the program with -g -O0 options
Next step through the program line by line in GDB, watch and understand what your program is doing. Look at the various variables. This is the essential debugging skill.
WHen it dies type the command 'k' this will give you a stack trace the last line of the trace will have the failing line number, but you know that anyway because you were on the line shen you did a step command
There is no "fget" in good old C, but maybe you're using a more modern version that has something named "fget". Most likely, you meant to use "fgetc". When a C I/O function starts with "f", it usually wants a FILE* handle as an argument, as "fgetc" does. Try using "fgetc" instead, after reading the documentation for it.