Split String Function in C

Question

I am trying to create a function in C that divides a string based on two spaces:

char *string = "10234540234  the";

I want get_weight() to return

10234540234

Here is how my function is defined

long get_weight(char *string) {
    long length = strlen(string);
    printf("%c \n", string[11]);
    char *number[200];
    int count = 0;
    for (int i = 0; i < length; i++) {
        if (string[i] == " " && string[i+1] == " ") {
            break;
        } else {
            number[count] = string[i];
            count++;
        }
    }
    return atol(number);
}

It goes into an infinite loop, and I am not sure why...

Fyi, return atol(number); should be flagging a compiler warning. The function requires const char *, you're passing anything-but. — WhozCraig
– WhozCraig, Commented Feb 16, 2021 at 17:50
You do realize just atol("123 xyz") would also return 123? — ilkkachu
– ilkkachu, Commented Feb 16, 2021 at 18:01
You would get the same result with long get_weight(char *string) { return atol(string); }. because atoi will stop at the first wrong character. For better error checking I suggest to use strtol instead of atol. — Bodo
– Bodo, Commented Feb 16, 2021 at 18:04

Damien · Accepted Answer · 2021-02-16 18:08:01Z

2

There were several issues in your code

Comparison of string[i] must be with a character
char number[200]; and not char *number[200];
Terminaison of the new string with '\0'

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

long get_weight(char *string) {
    long length = strlen(string);
    char number[200];
    int count = 0;
    for (int i = 0; i < length; i++) {
        if (string[i] == ' ' && string[i+1] == ' ') {
            break;
        } else {
            number[count] = string[i];
            count++;
        }
    }
    number[count] = '\0';
    return atol(number);
}

int main() {
    char str[] = "12346  abc";
    long num = get_weight (str);
    printf ("number = %ld\n", num);
}

Note that as mentioned in comments, if the goal is only to get the leading number, and not to split the input string as the title suggests, you could have only used

return atol(string);

edited Feb 16, 2021 at 18:08

answered Feb 16, 2021 at 17:57

Damien

4,8844 gold badges20 silver badges22 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Split String Function in C

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related