Convert a String to Float

Code

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

float custom_atof(const char *str) {
    float value=0;
    int dot=1, sign=1;
    if(*str == '-'){
        sign = -1;
        *str++;
    }
    else if(*str == '+'){
        sign = 1;
        *str++;
    }
    while(*str != '\0' && *str != '.'){
        value *=10;
        value +=*str - '0';
        ++str;
    }
    while(*str != '\0'){
        if(dot == 1){
            *str++;
            value *=10;
            value +=*str - '0';
            value /=10;
            dot =0;
        }
        else if(dot==0){
            value *=100;
            value +=*str - '0';
            value /=100;
            dot = -1;
        }
        str++;
    }
    return value * 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

 

 

 

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Input

123.45

Expected Output

123.45