Convert a String to Float

Code

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

float custom_atof(const char *str) {
    int sign = 1;
    float num = 0.0;
    float decimal_part = 0.1;
    
    if(*(str) == '-'){
        sign = -1;
        str++;
    } 
    else if(*str == '+'){
        str++;
    }
    
    while(*str >= '0' && *str <= '9'){
        num = num * 10 + (*str - '0');
        str++;
    }

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

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

    }

    return num * 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