Ex_3.6_itoa-3.c

/* a function of itoa, which accepts the third argument as the width of the number.
the string representation is padded with blanks in the left to get the  required width */

#include<stdio.h>
#include<string.h>

#define MAXLIMIT 100

void itoa(int n,char s[],int w);
void reverse(char s[]);

int main(void)
{
	int number,width;
	char str[MAXLIMIT];

	number= -343565;
	width=10;
	
	itoa(number,str,width);

	printf("%s",str);

	return 0;
}

void itoa(int n,char s[],int w)
{
	int i,sign;

	if((sign=n) < 0)
		n = -n;
	i=0;

	do
	{
		s[i++] = (n %10) + '0';

	}while((n/=10)>0);

	if(sign <0)
		s[i++]='-';

	while(i<w)
		s[i++]=' ';

	s[i]='\0';

	reverse(s);
}

void reverse(char s[])
{
	int i,j,c;

	for(i=0,j=strlen(s)-1;i<j;i++,j--)
		c=s[i],s[i]=s[j],s[j]=c;
}