Addition (+) does not want to run in if/else - c

Question

#include <stdio.h>
int main(void)
{
int a;
scanf("%d", &a);
for (int i = 0; ; i++)
{
char values[2];
scanf("%c", &values[0]);
scanf("%d", &values[1]);
if (values[0] == '*')
{
a = a * values[1];
printf(" = %d\n", a);
}
else if (values[0] == '+')
{
a = a + values[1];
printf(" = %d\n", a);
}
else if (values[0] == '%')
{
a = a % values[1];
break;
}
}
printf("%d", a);
}
When I input 5 + 3 + 7 + 10 + 2 + 3 + 1 % 11, it would show 5 (because 5%11 = 5). But the + operation didn't work. Can you see what is the problem here?

Answer 1

I think as values[2] is only two variable you need, you can use two different variable to do your job. use one char type variable and one int type variable as you need these two. You have another problem in your code, use a getchar() in the inside of the loop then your code will work fine, cause when you give a integer value as input then take a character value last you enter the new line that goes to that character that is why your code was giving error.
#include <stdio.h>
int main(void){
int a;
scanf("%d", &a);
for (int i = 0; ; i++)
{
getchar();
char ch;
int value;
scanf("%c", &ch);
scanf("%d", &value);
if (ch == '*')
{
a = a * value;
printf(" = %d\n", a);
}
else if (ch == '+')
{
a = a + value;
printf(" = %d\n", a);
}
else if (ch == '%')
{
a = a % value;
break;
}
}
printf("%d", a);
}

Answer 2

There are multiple problems:
value is an array of char: scanning the operator into a char is fine, but the value should be converted into an int variable.
the scanf("%c", ...) will store the next byte into the variable, but after converting an int, the next byte is the pending space or newline, not the '+'. You should use scanf(" %c", ...) to skip the whitespace after the previous conversion.
Here is a modified version:
#include <stdio.h>
int main(void) {
int a;
if (scanf("%d", &a) != 1)
return 1;
for (int i = 0; ; i++) {
char op;
int value;
if (scanf(" %c", &op) != 1)
break;
if (scanf("%d", &value) != 1)
break;
if (op == '*') {
a = a * value;
printf(" = %d\n", a);
} else
if (op == '+') {
a = a + value;
printf(" = %d\n", a);
} else
if (op == '-') {
a = a - value;
printf(" = %d\n", a);
} else
if (op == '%') {
a = a % value;
printf(" = %d\n", a);
} else
if (op == '/') {
a = a / value;
printf(" = %d\n", a);
} else {
printf("invalid operator %c\n", op);
break;
}
}
printf("%d\n", a);
return 0;
}