C Exercises: Convert a string to double

Last update on July 29 2025 12:57:21 (UTC/GMT +8 hours)

4. String to Double Conversion

Write a C program to convert a string to a double.

Sample Solution:

C Code:

#include<stdio.h>      // Include the standard input/output header file.
#include<stdlib.h>     // Include the standard library header file.

int main ()          // Start of the main function.
{
char input[] = "8.0 2.0";  // Declare a character array 'input' and initialize it with "8.0 2.0".
char * ptr_end;           // Declare a pointer to char 'ptr_end'.

double x, y;              // Declare two double variables 'x' and 'y'.

    x = strtod (input,&ptr_end);   // Convert the first part of 'input' to a double, store in 'x', and update 'ptr_end'.
    y = strtod (ptr_end,NULL);     // Convert the remaining part of 'input' to a double, store in 'y'.

printf ("\nOutput= %.2lf\n\n", x/y);   // Print the result of x/y with two decimal places.

return 0;   // Return 0 to indicate successful execution of the program.
}   // End of the main function.

Sample Output:

Output= 4.00

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to convert a floating-point string in scientific notation to a double using strtod().
Write a C program to convert a string with leading and trailing whitespace to a double and handle conversion errors.
Write a C program to convert a string to a double and verify that the conversion consumed the entire string.
Write a C program to convert a string to a double while handling locale-specific decimal separators.

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