Program For All Combination of the Given String in C

#include<stdio.h>

#include<string.h>

//char digits[]="0123456789";
char digits[10][5]={"ICON","CREW","FARM","OILY","CHOP","ARID","FUND","WAIT","GNAT","TEAR"};

char str[10];
int top=0;

void push(char a)
{
    str[top++]=a;
}

char pop()
{
    return(str[--top]);
}

void generate(char dig[15],int n)
{
    int i;
    char dig2[15];
    if(n==0)
    {
        push('\0');
        printf("\n %s",str);
        pop();
    }
    else
    {

        for(i=0;dig[i]!='\0';i++)
        {
            if(dig[i]!=' ')
            {
                strcpy(dig2,dig);
                push(dig[i]);
                dig2[i]=' ';
                generate(dig2,n-1);
                pop();
            }
        }
    }
}

void main()
{
    int i;

    for(i=0;i<10;i++)
    {
       
        generate(digits[i],4);
        
    }
}