CODEWITHSUNDEEP
c++stringpointerscharacter-encodingchar
user445338
user445338

Reputation:

C++ Weird encoded character added at the end of my char pointer

I have a function to convert infix notation to postfix notation. The only problem that I am having is that the last character of the produced postfix notation string is �

�

Any ideas what is happening? This is the function. If I print the infix char* passed as parameter it's printed correctly. It's when I print the postfix char* at the end of the function that I get � for the last character

   #include <iostream>
#include <string>
#include <fstream>
#include <string.h>
#include <ctype.h>
#include "queue.h"
#include "stack.h"

#define EXPRESSION_MAX_SIZE 50
#define MAX 10
#define EMPTY -1

using namespace std;

struct stack
{
    char data[MAX];
    int top;
};

Upvotes: 0

Views: 347

Answers (2)

Lou
Lou

Reputation: 1955

In copying line[] to infix[] in main():

for(unsigned int i=0; i<=line.size(); i++)
{
    infix[i] = line[i];
}

You failed to null terminate the infix array once you were done copying. The characters you are seeing are what was there at declaration time.

Upvotes: 2

Emile Cormier
Emile Cormier

Reputation: 29209

The gibberish character you're seeing is probably the EMPTY constant you're returning from pop on an empty stack. Stick an assert(!isempty(s)) in your pop function to make sure you're not trying to pop from an empty stack. If you run your program in a debugger, the debugger should show you the context (i.e stack trace) where the assert was triggered.

Trying to pop from an empty container reveals a serious flaw in a program. You shouldn't just return a special value, and hope that the callee bothers to check it. When detecting errors of this sort, it is wise to "fail immediately, and fail loudly". This will make it much easier to pinpoint the cause of errors. It'll also help ensure that bugs are detected before your program is deployed.

Upvotes: 2

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