Question

Command Line Arguments:

Write a program in C Compiler that will accept two integers on command line, subtract the second from the first (1st - 2nd) and display the answer.

It exactly two numbers are not provided on command line, there should be a simple error message printed and the program ends with no further input, output, or calculations

Answer 1

Here is the answer..

CODE:

#include<stdio.h>
int convert(char a[]) {
int i, s, start, n;

if (a[0] == '-') { //check if it is negative number
s = -1; //then store sign
}

if (s == -1) {
start = 1; //if negative number start with index 1
}
else {
start = 0; //if positive number start with index 0
}

n = 0;

for (i = start; a[i] != '\0'; i++) { //iterate through number
n = n * 10 + a[i] - '0';
}

if (s == -1) { //if sign -ve then make n as negative
n = -n;
}

return n; //return n
}

int main(int argc,char* argv[])
{
int counter;
if(argc==3)
{
int first=convert(argv[1]);
int second=convert(argv[2]);
printf("%d - %d = %d",first,second,first-second);
}
else
{
printf("Invalid arguments");
}
return 0;
}

OUTPUT:

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