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 sign = 1;
    int i = 0;

    if (str[0] == '-')
    {
        sign = -1;
        i++;
    }
    else if(str[0] == '+')
    {
        i++;
    }

    float value = 0;
    while(str[i] != '.' && str[i] != '\0')
    {
        value = (value * 10) + (str[i] - '0');
        i++;
    }

    float dec = 0;
    int cycles = 0;
    i++;
    while(str[i] != '\0')
    {
        dec = (dec * 10) + (str[i] - '0');
        i++;
        cycles++;
    }

    while (cycles > 0) 
    {
        dec = dec / 10;
        cycles--;
    }

    return (value + dec) * 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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