# Sum of digits in a string C++ Program

Sum of digits in a string C++ – find digits in a given string and calculate the sum of all digits. For example, if a given string is “hello65”; then sum of digits present in the string is 6+5 = 11.  isDigit() C++ library function will be used to check if char is a digits.

LOGIC:

• Traverse the string within a for loop.
• Check each character if it is a digit using isDigit() function.
• Convert digit character to int value and sum.

## Sum of digits in String C++ Code

``````/*-------------------------------------
* C++ program to extract digits from
* string and calculate the sum of them.
* */

#include <cctype>//For C++ isDigit() function
#include<iostream>
using namespace std;

//char to int conversion
#define charToInt(c) (c-'0')

int main()
{
int sum = 0;

std::string str = "hello65";

cout << "String contains digits :";

for (int i=0; i<str.length(); ++i)
{
//Check if char is digit
if (isdigit(str[i])){
//dispaly digit characters
cout << str[i] << ", ";

//convert charater to int
int a = charToInt(str[i]);

//Sum digits
sum = sum + a;
}

}
//Display Sum
cout<<"\nSum of all Digits:"<<sum<<endl;

return 0;
}``````

Program Output:
String contains digits :6, 5,
Sum of all Digits:11

Sum of digits in a string C++ Program

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