Convert a String to Float

Code

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

float custom_atof(const char *str) {
    int i = 0;
    float result  = 0;
    float sign = 1;
    float divisor = 10;

    if(str[i] == '-'){
        sign = -1;
        i++;
    }else if(str[i] == '+'){
        sign = 1;
        i++;
    }
    while(str[i] != '.' && str[i] != '\0'){
        result = (result * 10) + (str[i] - '0');
        i++;
    }
    i++;
    while(str[i] != '\0'){
        result = result + (str[i] - '0') / divisor;
        divisor = divisor * 10;
        i++;
    }

    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

 

 

 

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Input

123.45

Expected Output

123.45