what is the problem in my code??

general
1

hi…i am getting runtime error in this program plz help…

#include<stdio.h>
int main()
{
int cases,i,top=0;
char exp[400],stack[200];
scanf("%d",&cases);
while(cases)
{
scanf("%s",exp);
printf("\n");
for(i=0;exp[i];i++)
{
if(exp[i]==’(’)
continue;
if(exp[i]==’)’)
{
printf("%c",stack[top]);
top–;
}
else if(exp[i]==’+’ || exp[i]==’-’ || exp[i]==’*’ || exp[i]==’/’)
{
top++;
stack[top]=exp[i];
}
else
{
printf("%c",exp[i]);
}
}

cases–;
}
return 0;
}

2

I wasn’t able to figure out the error (sorry about that) but I found several errors in your code.

  1. the printf("\n") should be there after the evaluation and printing. You have put it at the top.

  2. Change the size of exp and stack to exp[401],stack[201]; The extra 1 is to store ‘\0’ when exp length is 400.

  3. Change the if statement to

if(exp[i]==’)’ && top>=0) //to avoid underflow

  1. Inside else statement where you print exp[i], add an if condition

if(exp[i]!=’)’ && exp[i]!=’(’)
printf("%c",exp[i])
Otherwise you are getting a ‘)’ in the output

  1. Initialize top to -1 not zero as you are always increasing it before storing the value in stack. Also initialize it for each test case inside the while loop. You have only initialized it once during declaration.

  2. Even after this, your code is giving wrong answer for the third sample test case. I hope someone else can point out the error behind that.


#include< stdio.h>
int main() 
{ 
	int cases,i,top=-1; 
	char exp[401],stack[201];		//extra 1 to store \0 
	scanf("%d",&cases); 
	while(cases) 
	{ 
		scanf("%s",exp); 
		//printf("\n"); 		//remove from here
		top=-1;
		for(i=0;exp[i];i++) 
		{ 
			if(exp[i]=='(') 
				continue; 
			if(exp[i]==')' && top>=0) 		//to avoid underflow
			{ 
				printf("%c",stack[top]); 
				top--; 
			} 
			else if(exp[i]=='+' || exp[i]=='-' || exp[i]=='*' || exp[i]=='/') 
			{ 
				top++; 
				stack[top]=exp[i]; 
			} 
			else 
			{ 
				if(exp[i]!=')' && exp[i]!='(')
					printf("%c",exp[i]); 
			}
		}
		printf("\n"); 
		cases--; 
	} 
	return 0; 
}
3

Please always provide a link to the problem or at least the problem code.

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