Convert a String to Float

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

float custom_atof(const char *str){
    int sign = 1;
    float num = 0.00f;
    float scale = 0.1f;

    if(*str == '+') str++;
    else if (*str == '-'){
        sign = -1;
        str++;
    }

    while(*str >= '0' && *str <= '9'){
        num = num*10+(*str - '0');
        str++;
    }

    if(*str == '.') str++;

    while(*str >= '0' && *str <= '9'){
        num += scale * (*str - '0');
        scale *= 0.1f;
        str++;
    }

    return sign * num;
}

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

    int i = 0;
    while(str[i]){
        if(str[i] == '\n'){
            str[i] = '\0';
            break;
        }
        i++;
    }
    printf("%.2f", custom_atof(str));
    return 0;
}