diff.c

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

char* intal_diff(const char* intal1, const char* intal2);
int intal_compare(const char *intal1, const char * intal2);

int main()
{
    const char intal_1[1000] = "0987657876789878909876567890";
    const char intal_2[1000] = "67876567890956765671";
    
    //intal_compare(intal1, intal2);
	printf("diff %s\n",intal_diff(intal_1, intal_2));
}

int intal_compare(const char* intal1, const char* intal2)
{   
    int len_1 = strlen(intal1);
    int len_2 = strlen(intal2);

   
    int diff_len = len_1 - len_2;

    

    if(diff_len < 0)
    {
        diff_len = diff_len * -1;
        char sol[len_2];
    }
    
    char* sol = malloc(sizeof(char*) * 1000);

    //printf("DIFF in len %d\n", diff_len);
    char zero[len_1+len_2];

    int i;
    for(i=0;i<diff_len;i++)
    {
        zero[i] = '0';
    }
   
   	zero[i] = '\0';	
   	
   // printf("%s\n", zero);
   // printf("%d\n",i);
    
    int x, y, res, carry;
    
    int p;
    
    
    carry = 0;
    
    int check = 0;
    
    if(len_1 < len_2)
    {
    	
    	 for (int j = 0; intal1[j] != '\0'; ++j, ++i)
    	 {
         	zero[i] = intal1[j];
   		 }
   		 
   		 zero[i] = '\0';
   		 
   		 //printf("zero   %s\n", zero);
    	 //printf("intal2 %s\n", intal2);
   		 
   		//Perform compare on zero and intal2
   		
   		for(p = 0; p <= len_2 -1; p++)
   		{
   			if(*(intal2 + p) - '0' > *(zero + p) - '0')
   			{
   				//printf("%d > %d\n",*(intal2 + p) - '0',*(zero + p) - '0');
   				//printf("-1\n");
   				return -1;
   			}
   			else if(*(intal2 + p) - '0' < *(zero + p) - '0')
   			{
   				//printf("%d < %d\n",*(intal2 + p) - '0',*(zero + p) - '0');
   				//printf("+1\n");
   				return 1;
   			}
   			else
   			{
   				//printf("%d= %d\n",*(intal2 + p) - '0',*(zero + p) - '0');
   				
   				
   			}
   			
   		}
   		//printf("0\n");
   		return 0;	
   		
    }
    else
    {
    	 int sol_index = 0;	
    	 for (int j = 0; intal2[j] != '\0'; ++j, ++i)
    	 {
         	zero[i] = intal2[j];
   		 }
   		  zero[i] = '\0';
   		 
   		 //printf("zero   %s\n", zero);
    	 //printf("intal1 %s\n", intal1);
   		 
    	
    	
    	//Perform compare on zero and intal1
    	
    	for(p = 0; p <= len_1 -1; p++)
   		{
   			if(*(intal1 + p) - '0' > *(zero + p) - '0')
   			{
   				//printf("%d > %d\n",*(intal1 + p) - '0',*(zero + p) - '0');
   				//printf("+1\n");
   				return 1;
   			}
   			else if(*(intal1 + p) - '0' < *(zero + p) - '0')
   			{
   				//printf("%d < %d\n",*(intal1 + p) - '0',*(zero + p) - '0');
   				//printf("-1\n");
   				return -1;
   			}
   			else
   			{
   				//printf("%d = %d\n",*(intal1 + p) - '0',*(zero + p) - '0');
   				
   			}
   			
   		}
   		printf("0\n");
   		return 0;
   		//printf("0\n");
   		
    }
    
}

char* intal_diff(const char* intal1, const char* intal2)
{
	int check = intal_compare(intal1, intal2);
	char* sol = malloc(sizeof(char*) * 1000);
	
	if(check == 1)
	{
		//intal1 - intal2
		
		
	    int len_1 = strlen(intal1);
		int len_2 = strlen(intal2);

	   
		int diff_len = len_1 - len_2;

		

		if(diff_len < 0)
		{
		    diff_len = diff_len * -1;
		    
		}
	

		//printf("DIFF in len %d\n", diff_len);
		char zero[len_1+len_2];

		int i;
		for(i=0;i<diff_len;i++)
		{
		    zero[i] = '0';
		}
	   
	   	zero[i] = '\0';	
	   	
		int sol_index = 0;	
    	
    	
        for (int j = 0; intal2[j] != '\0'; ++j, ++i)
        {
        	zero[i] = intal2[j];
   		}
   		 		
	   
	   	zero[i] = '\0';	
	   		
	   	//printf("intal1 %s - ",intal1); 
	   	//printf("intal2 %s\n",zero);
		
		//-----------------------------------------------------------------------------------------
		*(sol + strlen(zero)) = '\0';
		int B =0;
		int res;
		int p;
		for(p = strlen(zero)-1; p >= 0; p--)
   		{
   			int x = intal1	[p] - '0';
   			int y = zero[p] - '0';
   		   			
   			int res = (x - B) - y;
   			
   			if(res < 0)
   			{
   				res = res + 10;
   				B = 1;
   			}
   			else
   			{
   				B = 0;
   			}
   			//printf("res %d\n",res);
   			*(sol + p) = res + '0';
   			
   		}
   		
   		//printf("res %d\n",res);
		//printf("sol %s\n",sol);
		
		
		
	}
	
	else if(check == -1)
	{
		//intal2 - intal1
		
		//-----------------------------------------------------------------------------------------
		
		
	    int len_1 = strlen(intal1);
		int len_2 = strlen(intal2);

	   
		int diff_len = len_1 - len_2;

		

		if(diff_len < 0)
		{
		    diff_len = diff_len * -1;
		}
		

		//printf("DIFF in len %d\n", diff_len);
		char zero[len_1+len_2];

		int i;
		for(i=0;i<diff_len;i++)
		{
		    zero[i] = '0';
		}
	 	
	 	zero[i] = '\0';	
	 		
	 	int sol_index = 0;	
    	
    	
        for (int j = 0; intal1[j] != '\0'; ++j, ++i)
        {
        	zero[i] = intal1[j];
   		}
   		 		
	   
	   	zero[i] = '\0';	
	   	
	   	
		//printf("intal2 %s - ",intal2); 
		//printf("intal1 %s\n",zero);
		
		
		//-----------------------------------------------------------------------------------------
		
		*(sol + strlen(zero)) = '\0';
		
		int B =0;
		int res;
		
		int p;
		
		for(p = strlen(zero) -1; p >= 0; p--)
   		{
   			int x = intal2[p] - '0';
   			int y = zero[p] - '0';
   		   			
   			int res = (x - B) - y;
   			
   			if(res < 0)
   			{
   				res = res + 10;
   				B = 1;
   			}
   			else
   			{
   				B = 0;
   			}
   			//printf("res %d\n",res);
   			*(sol + p) = res + '0';
   			
   		}
   		
   		//printf("res %d\n",res);
		//printf("sol %s\n",sol);
		
		
			
	}
	else
	{
		//intal1 == intal2
		
		
		return "0";	
	}
	
	 while(*(sol + 0) == '0')
    {
    	sol++;
    }
    
	
	return sol;
}