I'm trying to make an addition ( ) with the numbers of a string. I have tried to do this:

void add_numbers(string z)
{
    char result = 0;
    for (int i = 0; i < strlen(z); i  )
    {
        result = result   z[i];
    }
    printf("%c", result);
}

int main(void)
{
    string z = "2222";
    add_numbers(z);
}

The output should be 10, because 2 2 2 2 = 10. But, actually, the output is ]0;

What am I doing wrong?

CodePudding user response：

The variable "result" is not char. It must be int.

CodePudding user response：

#include <stdio.h>

typedef char* string;
void add_numbers(string z)
{
    int result = 0;
    while(*z)
    {
        result  =*z  -'0';  // I love the symbol sequence here:  =*z  -'0';
    }
    printf("%d", result);
}

int main(void)
{
    string z = "2222";  // Correct answer is 8
    add_numbers(z);
}

Output

Success #stdin #stdout 0.01s 5444KB
8

IDEOne Link

CodePudding user response：

Don't use char for 'result' (it is prone to UB as it will easily overflow), instead use something like int. You also cannot use the '%c' format specifier in printf, as it will print the character representation of its argument. You also have to remember the characters of a string are (not guaranteed, but most likely) stored in ASCII format, where the numerical characters do not correspond to their actual integer numbers. Subtract a '0' from each digit to accomodate for this.

result = result   z[i];

should be

result = result   z[i] - '0';

or even better

result  = z[i] - '0';