Convert String to Integer

Code

#include <stdio.h>
#include <stdint.h>

int custom_atoi(const char *str) {
    // Your logic here
    char *ptr;
    int n;
    ptr = (char *) str;
    if ((*ptr == '+') || (*ptr == '-')) {
        ptr++;
    }
    while ((*ptr >= '0') && (*ptr <= '9')) {
        ptr++;
    }
    *ptr = '\0';
    sscanf(str, "%d", &n);
    return n;
}

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);

    // Remove newline
    uint8_t i = 0;
    while (str[i]) {
        if (str[i] == '\n') {
            str[i] = '\0';
            break;
        }
        i++;
    }

    printf("%d", custom_atoi(str));
    return 0;
}

Solving Approach

Allow an optional leading '+' or '-'

then scan for first non-digit and use it to terminate the string and forward it to sscanf to read it