Convert a String to Float

Code

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

float custom_atof(const char *str) {
    float result = 0;
    char *tmp = (char *)str;
    int sign = 1;
    
    if(*tmp == '-') {
        ++tmp;
        sign = -1;
    }
    if (*tmp == '+') {
        ++tmp;    
    }

    int ipart = 0;
    int fpart = 0;
    int fpart_size = 0;

    while(*tmp != '\0' && *tmp != '.') {
        ipart = (ipart * 10) + (*tmp - '0');
        ++tmp;
    }
    if (*tmp == '\0') {
        return ipart * sign;
    }
    ++tmp;
    while(*tmp != '\0') {
        fpart = (fpart * 10) + (*tmp - '0');
        ++tmp;
        ++fpart_size;
    }

    result = fpart;
    for (int i = 0; i < fpart_size; ++i) {
        result /= 10.0f;
    }
    result += (float)ipart;
    
    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++;
    }

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

Solving Approach