Convert String to Integer

Code

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

int custom_atoi(const char *str) {
    // Your logic here
    int sign = 0;
    int result = 0;
    bool nbr = false;
    while (*str){
        if ((!(sign)) && ((*str == '-') || (*str == '+'))) { //determine sign
            if (*str=='-') sign = -1;
            else if (*str=='+') sign = 1;
        }
        else
        if ((*str >= '0') && (*str <='9')) { //is number
            result = result*10 + ((char)*str - '0');
            nbr = true; //space not accepted anymore
            if (!(sign)) sign = 1; //no +/- at start

        }
        else  //not number 
            if ((*str==' ') && (!nbr)) {} //just ignore
            else return (result * sign);
            
    str++;

    }
    return (result * sign);
}

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

 

 

 

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Input

123abc

Expected Output

123