CS456 - Systems Programming Spring 2026

Displaying ./code/jan28/printnums.c

/*

printnums.c - printing all numbers from 1 to a specified number

Compilation and output:
> gcc -o printnums printnums.c
> ./printnums 
Usage ./printnums number
> ./printnums 6
1
2
3
4
5
6

*/


#include <stdio.h>
#include <stdlib.h> //needed for exit and atoi functios

int main(int argc, char **argv){

	//printing usage statement if number is not provided
	if(argc < 2){
		fprintf(stderr, "Usage %s number\n", argv[0]);
		exit(-1);
	}

	// everything stored in argv is a string
	// we need to convert it to an integer before we can use it
	// atoi accomplishes this objective
	int endNum = atoi(argv[1]);

	//then use for loop to print from 1 to the specified number
	for(int i = 1; i <= endNum; i++)
		printf("%d\n", i);

	return 0;

}