Please help whats is the logical error ... Compile and run the code and check .. Y does it give unexpected error

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<math.h>

int main()
{
	int a=0,b=0;
	int sum,diff,mult,R;
	float div;
	char c,ch;

do
{
	printf("\n\n\tENTER THE FIRST operand   ");
	scanf("%d",&a); //takes value for a for eg 7
	printf("\n\n\tENTER THE SECOND operand   ");
	scanf("%d",&b);//takes value for b for eg 4
	printf("\t\n\n_______________________________");
	printf("\t | ENTER THE DESIRED OPERATOR |");
	printf("\t_______________________________");
	printf("\n\n \t\tFOR SUMMATION PRESS +  \n\n \t\tFOR DIFFERENCE PRESS -  \n\n \t\tFOR PRODUCT PRESS * \n\n \t\tFOR DIVISION PRESS / \n\n \t\tTO FIND REMAINDER ONLY PRESS %% \n\n \t\tPRESS 0 TO EXIT\n\n");
	scanf("%s",&c);
	printf("\t\n\n  OPERATION TO BE PERFORMED IS '%c' PRESS ANY KEY TO CONTINUE",c);
	getch();

 if(c=='+'||c=='-'||c=='*'||c=='/'||c=='%'||c=='0')
{
	printf("\n\n |RESULTS|");

	if(c=='-')
	{	
	diff=a-b;
	printf("\n\nDIFFERENCE OF %d AND %d IS : %d \n\n",a,b,diff);// here it should give output as 7-4=3 but it gives 7-0=7 . why is it so
getch();
}  else if(c=='+')
{	
	sum=a+b;
	printf("\n\n\tSUMMATION OF %d AND %d IS : %d \n\n",a,b,sum);
	getch();
} else if(c=='*')
{	
	mult=a*b;
	printf("\n\n\tPORDUCT OF %d AND %d IS : %d \n\n",a,b,mult);
	getch();
} else if(c=='/')
{	
	div=a/(float)b;
	printf("\n\n\tDIVISION OF %d AND %d IS : %f \n\n",a,b,div);
	getch();
} else if(c=='%')
{	
	R=a%b;
	printf("\n\n\tREMAINDER WHEN %d IS DIVIDED BY %d IS : %d \n\n",a,b,R);
	getch();
}
}
else {
	printf("\n\n\n\t\t\t  INVALID OPERATOR ENTER CORRECT OPERATOR ");
	getch();
}

}while(c!= '0');
return 0;
}