Thread: Using putchar to output an integer with more than 1 digit

Hi, I'm trying to create a program that does simple C arithmetic calculations (such as 12 + 12). There can be multiple blanks before and after an operand. The expression and result and expression is supposed to be displayed like 12+12=24, where the expression (12+12) must be output from only using putchar. The = and result (24) can be used with a printf function, but anything dealing with the expression can not be used with printf (putchar only.) So far, I just want to know how I can store the operand (12 for example) and output it.

Code:

#include <stdio.h>

int convert(void);

int main(void)
{
	int op1;
	op1 = convert();

	printf("%d", op1);

	return 0;

}


int convert(void)
{
	int iochar,
		sum = 0;
	while(((iochar = getchar() ) != ' ' ) && (iochar != '\n' ) )
	{
		sum = sum * 10 + (iochar - '0');
	}
	return (sum);
}

The code I have above was used mostly from a convert function from my programming book which reads from standard input until either a blank or end of line is found. It works, but only because printf function is being used in main. If I enter something such as putchar(op1); instead of printf("%d", op1);, I get some awkward results (symbols, alt codes, etc.) Any advice would be highly appreciated, I just want to know how I can store the integer (with more than 1 digit) using getchar and also output it using putchar. I've also tried tackling the problem with a different piece of code, but only the first number of the operand would be output (instead of 12, it would only output 1.)

Dup post: Mods, please delete.