Convert a String to Float

Code

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

float custom_atof(const char *str) {
    int i = 0;
    int sign = 1;
    float result = 0.0f;
    float frac_part = 0.0f;
    float divisor = 1.0f;
    int after_decimal = 0;

    
    while (str[i] == ' ')
        i++;

   
    if (str[i] == '-') {
        sign = -1;
        i++;
    } else if (str[i] == '+') {
        i++;
    }

   
    while (str[i] != '\0') {
        if (str[i] >= '0' && str[i] <= '9') {
            if (after_decimal) {
                divisor *= 10.0f;
                frac_part = frac_part * 10 + (str[i] - '0');
            } else {
                result = result * 10 + (str[i] - '0');
            }
        } else if (str[i] == '.') {
            
            if (after_decimal)
                break;  
            after_decimal = 1;
        } else {
            
            break;
        }
        i++;
    }

    result = result + frac_part / divisor;
    return sign * result;
}

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++;
    }

    float value = custom_atof(str);
    printf("%.2f", value);
    return 0;
}

Solving Approach