Convert a String to Float

Code

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

float custom_atof(const char *str) {
    uint8_t i = 0;
    float res = 0;
    float frac = 0 ;
    int sign = 1;
    int in_fraction = 0;
    float div = 10.0;

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

    while (str[i] != '\0') {
        if (str[i] == '.') {
            in_fraction = 1;
            i++;
            continue;
        }
        if (str[i] <= '9' && str[i] >= '0') {
            int digit = str[i] - '0';
            if (!in_fraction) {
                res = res * 10.0 + digit;
            } else {
                frac += digit / div;
                div *= 10.0;
            }
        } else {
            break;
        }
        i++;
    }
    return (res + frac) * 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++;
    }

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

Solving Approach