Sai A Sai A
Updated date Jan 17, 2024
In this blog, we will learn how to turn words into numbers in C. Learn step by step with easy examples, exploring different ways to change text to decimal values.

Introduction:

When working with C programming, handling data of different types is a common task. One frequent challenge is converting strings to doubles, a process important in scenarios such as user input processing or data parsing. In this blog, we will explore multiple methods to achieve this conversion in C,

Method 1: Using Standard Library Functions (strtod)

The C Standard Library provides a convenient function, strtod, specifically designed for converting strings to doubles. Let's take a look at a simple program utilizing this method:

#include <stdio.h>
#include <stdlib.h>

int main() {
    char str[] = "3.14";
    double result = strtod(str, NULL);

    printf("Method 1 Output: %.2f\n", result);

    return 0;
}

Here, the strtod function takes a string (str) as its first argument and converts it to a double. The second argument (NULL in this case) is used to capture the end of the conversion process, which can be useful for error handling. The result is then printed to the console using printf.

Output:

Method 1 Output: 3.14

Method 2: Using sscanf

 Another method involves using the sscanf function, which is used for reading formatted input from strings. Here's an example program:

#include <stdio.h>

int main() {
    char str[] = "2.718";
    double result;

    sscanf(str, "%lf", &result);

    printf("Method 2 Output: %.3f\n", result);

    return 0;
}

In this example, the sscanf function is employed with the format specifier %lf to indicate that the input should be interpreted as a double. The result is then stored in the variable result and printed to the console.

Output:

Method 2 Output: 2.718

Method 3: Using atof Function

C also provides the atof function, which is short for "ASCII to float." While this function is designed for floats, it can be used for doubles as well:

#include <stdio.h>
#include <stdlib.h>

int main() {
    char str[] = "42.0";
    double result = atof(str);

    printf("Method 3 Output: %.1f\n", result);

    return 0;
}

The atof function takes a string as input and converts it to a floating-point number. In this example, the resulting float is implicitly cast to a double when assigned to the variable result, and the value is then printed to the console.

Output:

Method 3 Output: 42.0

Conclusion:

In this blog, we have discussed various methods for converting strings to doubles in C. We have covered the use of the strtod function from the Standard Library, the sscanf function for formatted input, and the atof function designed for ASCII to float conversion.

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