I've checked similar questions posted here on the forum, but none of those answers my question.
I have a string (char s []) and I want to 'copy' the numbers in that string to another one (char n []).
Here's my attempt at this:
char s[] = "oa323shsh123383.33hbabsa3€"
int len = strlen(s);
char n[];
int k;
for (k = 0; k <= len; k++){
if( s[k] >= '0' || s[k] <= '9') {
n[k] = s[k] - 48;
}
}
However this is wrong, because it doesn't print out anything. Can anybody help me ?
Use && in your IF.
Allocate your array n. Easy way is to declare n as
char n[] = char[len+1];
Use another variable to count the number being added to n, otherwise you will have n being:
"..323....123383" etc
Should end up with something like
char s[] = "oa323shsh123383.33hbabsa3€"
int len = strlen(s);
char n[] = char[len+1];
int k, j=0;
for (k = 0; k <= len; k++){
if( s[k] >= '0' && s[k] <= '9') {
n[j] = s[k] - 48;
n[j+1] = '\0';
j++;
}
}
char s[] = "oa323shsh123383.33hbabsa3€";
int len = strlen(s);
char* n = (char*) malloc(len+1);
int i,j=0;
for (i = 0; i < len; ++i)
{
if( s[i] >= '0' && s[i] <= '9')
n[j++] = s[i];
}
n[j]=0;
n is now a printable string
dont forget to free it when you are done.
Related
I need to check if a given string is a Palindrome or mini-Palindrome.
Palindrome length will be 2 or more, the function need to ignore spaces and ignore the differences of upper and lower alphabet.
if the string is Palindrome the function will transfer the indexes of the start and the end of him and will return 1 else return 0.
example1: "My gym" the function will transfer low=0 high=5 and 1
example2: "I Love ANNA" the function will transfer low=7 high=10 and 1
example3: "I love Pasta" return 0.
Also i can’t use functions from librarys other then string.h stdlib.h stdio.h.
I tried to write like this:
int i;
int size = strlen(str);
i = 0;
while (str[i] != '\0')
{
if (str[i] == ' ')
{
i++;
continue;
}
//-------------------
if (str[i] >= ‘a’ && str[i] <= ‘z’)
str[i] = str[i] - 32;
if (str[size-1] >= ‘a’ && str[size-1] <= ‘z’)
str[size-1] = str[size-1] - 32;
//-------------------
if (str[i] == str[size-1])
{
*low = i;
*high = size-1;
return 1;
}
else
{
size--;
i++;
}
}
return 0;
But it isnt working well, i cant figure how to do it with the example 2
Here goes. Will this help you
#define LOWER(a) (((a) >=' A' && (a) <= 'Z') ? ((a) - 'A' +'a') : (a))
#define MYCMP(a,b) (LOWER(a) == LOWER(b))
int is_palidrome(char *s) {
int start = 0;
int end = strlen(s) - 1;
for (; s[start] // Not end of line
&& end >=0 // Not run over the from of the line
&& start < end // Still not got to the middle
&& MYCMP(s[start], s[end]) == 1; // They are still equal
start++, end--) { //Nowt }
};
return (start >= end);
}
I made a program. It works only if the string contains letters and spaces. You can modify it to work for other characters.
#include <stdio.h>
#include <string.h>
#define SIZE 100
int isPalindrome( char *s, size_t l );
int main() {
char str[SIZE];
size_t i, j, len, pldrm = 0;
fgets(str, SIZE, stdin);
len = strlen(str);
for(i = 0; i < len; i++) if( str[i] != ' ' && !((str[i] >= 'a' && str[i] <= 'z') || (str[i] >= 'A' && str[i] <= 'Z')) ) goto the_end;
for(i = 0; i < len-1; i++) {
if( str[i] != ' ' ) {
for(j = i+1; j < len; j++) {
if( (pldrm = isPalindrome(&str[i], j-i+1)) ) {
str[j+1] = '\0';
goto the_end;
}
}
}
}
the_end:
pldrm ? printf("A palindrome has been found from the position %zu till the position %zu.\n\nThe palindrome is: %s\n", i, j, &str[i]) : puts("No palindromes");
return 0;
}
int isPalindrome( char *s, size_t l )
{
static const char az[26] = "abcdefghijklmnopqrstuvwxyz", AZ[26] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
int isPldrm = 1, spc = 0; // used to skip spaces within the palindrome
for(size_t i = 0; i < l/2; i++) {
for(size_t j = 0; j < 26; j++) {
if( s[i] == az[j] || s[i] == AZ[j] ) {
while( s[l-1-i-spc] == ' ' ) ++spc;
if( s[l-1-i-spc] != az[j] && s[l-1-i-spc] != AZ[j] ) {
isPldrm = 0;
goto thats_it;
}
break;
}
}
}
thats_it:
return isPldrm;
}
Also, it finds only the first palindrome in the input. Doesn't check for further palindromes.
For example: Say that the string is "90.%7."
The function would filter out the % and the second dot.
The function would thus return "90.7"
I'm flexible as to how it would return it.
Everything i have done so far hasn't worked. Sad Face.
Thanks.
Edit: I figured out how to do it.
Check out this code
void filter(const char * input, char * output)
{
int length = strlen(input);
int dot_was_seen = 0;
int i;
int j = 0;
for( i = 0 ; i < length ; i++)
{
if(input[i] >= 0x30 && input[i] <= 0x39)
output[j++] = input[i];
else if(!dot_was_seen && input[i] == 0x2E)
{
output[j++] = input[i];
dot_was_seen = 1;
}
}
output[j] = 0;
}
int main()
{
char input[] = "90.%7.";
char output[32];
filter(input, output);
printf(output);
return 0;
}
Sorry for such a mediocre question, but I ran into what seems to be a tiny problem, but simply can't get over it. For my task I have to take a line of string from a file, and put it into another file backwards, for example:
one two three
four five six
would be
three two one
six five four
My problem is, is that I'm getting
three two one
si five four
So basically the flaw is that there is a space character at the beginning of each line and the last letter of the last word is always missing. Here's my reverse function:
void reverse(char input[], int length, char output[]) {
char space = 32;
input[length - 1] = space;
int value = 0;
int i, k = 0, j;
for (i = 0; i <= length; i++) {
if (input[i] == space) {
for (j = i - 1; j >= k; j--, value++) {
output[value] = input[j];
}
if (j == -1) {
output[value] = space;
value++;
}
k = i;
}
}
char c = 0;
for (int i = 0, j = length - 1; i <= j; i++, j--) {
c = output[i];
output[i] = output[j];
output[j] = c;
}
}
What I'm doing is first reversing each word by character, and then the whole line. If someone could help me find the last bits that I've missed I would greatly appreciate it.
The flaws come from your approach:
why do you force a space at offset length - 1? If you read the line with fgets(), there is probably a newline ('\n') at the end of the line, but it might be missing at the end of the input, which would explain the x getting overwritten on the last line.
you should not modify the input buffer.
Here is a simplified version, along with a simple main function:
#include <stdio.h>
#include <string.h>
void reverse(const char *input, int length, char *output) {
int i, j, k, v;
for (i = k = v = 0;; i++) {
if (i == length || input[i] == ' ') {
for (j = i; j-- > k; v++) {
output[v] = input[j];
}
for (; i < length && input[i] == ' '; i++) {
output[v++] = ' ';
}
if (i == length) {
output[v] = '\0';
break;
}
k = i;
}
}
for (i = 0, j = length - 1; i < j; i++, j--) {
char c = output[i];
output[i] = output[j];
output[j] = c;
}
}
int main() {
char input[256];
char output[256];
while (fgets(input, sizeof input, stdin)) {
reverse(input, strcspn(input, "\n"), output);
puts(output);
}
return 0;
}
Output:
three two one
six five four
Here is a simpler reverse function that operates in one pass:
#include <string.h>
void reverse(const char *input, int length, char *output) {
int i, j, k, v;
for (i = k = 0, v = length;; i++) {
if (i == length || input[i] == ' ') {
for (j = i; j-- > k;) {
output[--v] = input[j];
for (; i < length && input[i] == ' '; i++) {
output[--v] = ' ';
}
if (v == 0) {
output[length] = '\0';
break;
}
k = i;
}
}
}
Replace input[length - 1] = space; with input[length] = space;
My program is designed to allow the user to input a string and my program will output the number of occurrences of each letters and words. My program also sorts the words alphabetically.
My issue is: I output the words seen (first unsorted) and their occurrences as a table, and in my table I don't want duplicates. SOLVED
For example, if the word "to" was seen twice I just want the word "to" to appear only once in my table outputting the number of occurrences.
How can I fix this? Also, why is it that i can't simply set string[i] == delim to apply to every delimiter rather than having to assign it manually for each delimiter?
Edit: Fixed my output error. But how can I set a condition for string[i] to equal any of the delimiters in my code rather than just work for the space bar? For example on my output, if i enter "you, you" it will out put "you, you" rather than just "you". How can I write it so it removes the comma and compares "you, you" to be as one word.
Any help is appreciated. My code is below:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
const char delim[] = ", . - !*()&^%$##<> ? []{}\\ / \"";
#define SIZE 1000
void occurrences(char s[], int count[]);
void lower(char s[]);
int main()
{
char string[SIZE], words[SIZE][SIZE], temp[SIZE];
int i = 0, j = 0, k = 0, n = 0, count;
int c = 0, cnt[26] = { 0 };
printf("Enter your input string:");
fgets(string, 256, stdin);
string[strlen(string) - 1] = '\0';
lower(string);
occurrences(string, cnt);
printf("Number of occurrences of each letter in the text: \n");
for (c = 0; c < 26; c++){
if (cnt[c] != 0){
printf("%c \t %d\n", c + 'a', cnt[c]);
}
}
/*extracting each and every string and copying to a different place */
while (string[i] != '\0')
{
if (string[i] == ' ')
{
words[j][k] = '\0';
k = 0;
j++;
}
else
{
words[j][k++] = string[i];
}
i++;
}
words[j][k] = '\0';
n = j;
printf("Unsorted Frequency:\n");
for (i = 0; i < n; i++)
{
strcpy(temp, words[i]);
for (j = i + 1; j <= n; j++)
{
if (strcmp(words[i], words[j]) == 0)
{
for (a = j; a <= n; a++)
strcpy(words[a], words[a + 1]);
n--;
}
} //inner for
}
i = 0;
/* find the frequency of each word */
while (i <= n) {
count = 1;
if (i != n) {
for (j = i + 1; j <= n; j++) {
if (strcmp(words[i], words[j]) == 0) {
count++;
}
}
}
/* count - indicates the frequecy of word[i] */
printf("%s\t%d\n", words[i], count);
/* skipping to the next word to process */
i = i + count;
}
printf("ALphabetical Order:\n");
for (i = 0; i < n; i++)
{
strcpy(temp, words[i]);
for (j = i + 1; j <= n; j++)
{
if (strcmp(words[i], words[j]) > 0)
{
strcpy(temp, words[j]);
strcpy(words[j], words[i]);
strcpy(words[i], temp);
}
}
}
i = 0;
while (i <= n) {
count = 1;
if (i != n) {
for (j = i + 1; j <= n; j++) {
if (strcmp(words[i], words[j]) == 0) {
count++;
}
}
}
printf("%s\n", words[i]);
i = i + count;
}
return 0;
}
void occurrences(char s[], int count[]){
int i = 0;
while (s[i] != '\0'){
if (s[i] >= 'a' && s[i] <= 'z')
count[s[i] - 'a']++;
i++;
}
}
void lower(char s[]){
int i = 0;
while (s[i] != '\0'){
if (s[i] >= 'A' && s[i] <= 'Z'){
s[i] = (s[i] - 'A') + 'a';
}
i++;
}
}
I have the solution to your problem and its name is called Wall. No, not the type to bang your head against when you encounter a problem that you can't seem to solve but for the Warnings that you want your compiler to emit: ALL OF THEM.
If you compile C code with out using -Wall then you can commit all the errors that people tell you is why C is so dangerous. But once you enable Warnings the compiler will tell you about them.
I have 4 for your program:
for (c; c< 26; c++) { That first c doesn't do anything, this could be written for (; c < 26; c++) { or perhaps beter as for (c = 0; c <26; c++) {
words[i] == NULL "Statement with no effect". Well that probably isn't what you wanted to do. The compiler tells you that that line doesn't do anything.
"Unused variable 'text'." That is pretty clear too: you have defined text as a variable but then never used it. Perhaps you meant to or perhaps it was a variable you thought you needed. Either way it can go now.
"Control reaches end of non-void function". In C main is usually defined as int main, i.e. main returns an int. Standard practice is to return 0 if the program successfully completed and some other value on error. Adding return 0; at the end of main will work.
You can simplify your delimiters. Anything that is not a-z (after lower casing it), is a delimiter. You don't [need to] care which one it is. It's the end of a word. Rather than specify delimiters, specify chars that are word chars (e.g. if words were C symbols, the word chars would be: A-Z, a-z, 0-9, and _). But, it looks like you only want a-z.
Here are some [untested] examples:
void
scanline(char *buf)
{
int chr;
char *lhs;
char *rhs;
char tmp[5000];
lhs = tmp;
for (rhs = buf; *rhs != 0; ++rhs) {
chr = *rhs;
if ((chr >= 'A') && (chr <= 'Z'))
chr = (chr - 'A') + 'a';
if ((chr >= 'a') && (chr <= 'z')) {
*lhs++ = chr;
char_histogram[chr] += 1;
continue;
}
*lhs = 0;
if (lhs > tmp)
count_string(tmp);
lhs = tmp;
}
if (lhs > tmp) {
*lhs = 0;
count_string(tmp);
}
}
void
count_string(char *str)
{
int idx;
int match;
match = -1;
for (idx = 0; idx < word_count; ++idx) {
if (strcmp(words[idx],str) == 0) {
match = idx;
break;
}
}
if (match < 0) {
match = word_count++;
strcpy(words[match],str);
}
word_histogram[match] += 1;
}
Using separate arrays is ugly. Using a struct might be better:
#define STRMAX 100 // max string length
#define WORDMAX 1000 // max number of strings
struct word {
int word_hist; // histogram value
char word_string[STRMAX]; // string value
};
int word_count; // number of elements in wordlist
struct word wordlist[WORDMAX]; // list of known words
Hi this is my first question here so I apologize if I didn't follow all the rules for posting. This is K&R exercise 2-3 and I'm getting a segmentation fault when compiling with GCC and I'm not familiar with the debugger to understand what's going on. I'd be grateful if anyone could glance over the code and help me with what went wrong.
#include <stdio.h>
#define HEX 16
unsigned int htoi(char s[]) {
int i, len, n, rp, v;
v = 0;
if (s[0] == '0')
if (s[1] == 'x' || s[1] == 'X')
s[1] = '0';
for (len = 0; len != '\0'; ++len) {
}
for (i = len; i >= 0; --i) {
if (s[i] >= '0' && s[i] <= '9')
n = s[i] - '0';
else if (s[i] >= 'A' && s[i] <= 'F')
n = s[i] - 'A' + 10;
else if (s[i] >= 'a' && s[i] <= 'f')
n = s[i] - 'a' + 10;
rp = len - i;
v += n * HEX^rp;
}
return v;
}
int main() {
int test = htoi("0x1a9f");
printf("%d\n", test);
return 0;
}
You are passing the address of a string literal which is read-only. Doing the following will get rid of the segmentation fault.
char temp[] = "0x1a9f";
int test = htoi(temp);
Also:
v += n * HEX^rp;
Is ^ is the XOR operator and not the power operator. For power you need the pow function in math.h
Also:
for (i = len; i >= 0; --i) should be for (i = len - 1; i >= 0; --i) because the value of len goes out of the bound of the array. (Notified by #Grijesh Chauhan and #simonc)
int test = htoi("0x1a9f");
passes the string literal "0x1a9f" to htoi. This may exist in read-only memory and cannot be modified. You therefore get undefined behaviour (with a crash a valid example of this) when you try to write to the string in the line
s[1] = '0';
The easiest fix is to copy the original string into a modifiable variable
char s[] = "0x1a9f";
int test = htoi(s);
As reported by Grijesh, further into htoi, you also read beyond the bounds of the string
for (i = len; i >= 0; --i)
should be:
for (i = len - 1; i >= 0; --i)