100. Convert a String to Float

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Code

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

float custom_atof(const char *str) {
    // Your logic here
    int dotIndex = 0;
    float output = 0;
    float divisor = 10.0;
    bool sign = 0;
    for (int i = 0; str[i] != '\0'; i++){
        if(str[i] == '-'){
            sign = 1;
        } else if (str[i] == '+'){
            ;
        } else if (str[i] == '.'){
            dotIndex = i;
        } else if (str[i] >= '0' && str[i] <= '9') {
            if (!dotIndex) {
                output = 10.0 * output + (str[i] - '0');
            } else {
                output = output + (str[i] - '0') / divisor;
                divisor *= 10.0;
            }
        }
    }
    if (sign){
        output = 0.0 - output;
    }
    return output;
}

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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