Char to int C program

Conversion of char to int C program – Convert a character digit to the corresponding integer in C program. For example, if the character is ‘5’ (char c =’5’) then corresponding int number will be 5.

The conversion is very simple and just we have to Subtract ‘0’ like below example.
int i = c – ‘0’;

How subtracting ‘0′ help find char to int digit?

Subtracting the decimal ASCII value of 0 (zero) from decimal ASCII value of entered digit into char format results to corresponding digit. For example,  consider the char digit ‘5’, its decimal ASCII value is 53 and 0 has decimal ASCII value 48. On subtraction it gives int value 5. (‘5’ -‘0’ =>  53 – 48 = 5).

Char to int C Program example

#include<stdio.h>

/*------ Char to int digit conversion --------*/
//parameter : pass char
//return : int (converted corresponding digit)
int charToInt(char c){
	int num = 0;

	//Substract '0' from entered char to get
	//corresponding digit
	num = c - '0';

	return num;
}

/* You can write one liner statement e.g.
int charToInt(char c){

return c - '0';
}
*/

int main(){
	char c;
	int numer=0;

	printf("Enter digit Character :");
	scanf("%c",&c);

	numer = charToInt(c);
	printf("Character %c -> number %d",c,numer);

	return 0;
}

Output:
Enter digit Character :5
Character 5 -> number 5