Show function, variable

Tells us next to nothing.

Shown exactly what you tried.
Describe exactly what you did with it.
Describe what you expected to happen.
Describe what actually to happened.
What testing/investigation/debugging have you done to account for the discrepancy?

When actual behaviour differs from expected behaviour, first check your expectations.

Tells us next to nothing.

Shown exactly what you tried.
Describe exactly what you did with it.
Describe what you expected to happen.
Describe what actually to happened.
What testing/investigation/debugging have you done to account for the discrepancy?

When actual behaviour differs from expected behaviour, first check your expectations.

Ok, so I tried this below (see code). I debuged the program and I wirote to Command Window variable x and then y. I'm expecting a result when pcStr1[] == pcStr2[] then should return EQUAL otherwise DIFFERENT - I want to see this.
I saw that for the value x (stands for EQUAL) assign value 0x00000001 for y 0x00000000.

#include <LPC21xx.H>
#include <stdio.h>
#include <string.h>

#define NULL 0

enum CompResult{DIFFERENT, EQUAL};

enum CompResult eCompareString(char pcStr1[], char pcStr2[]){

        unsigned char ucCounter;

        for(ucCounter=0; pcStr1[ucCounter]==pcStr2[ucCounter]; ucCounter++){
                if(pcStr1[ucCounter]==NULL){
                        return EQUAL;
                }
        }
        return DIFFERENT;
}

int main(){

        char pcStr1[] = {'a','b','c', NULL};
        char pcStr2[] = {'d','e','f', 'e', NULL};

        static volatile int x;
        static volatile int y;
        x = EQUAL;
        y = DIFFERENT;

        eCompareString(pcStr1, pcStr2);
        x;
        y;

}

So how do you expect the value of either x or y to get changed by the code you showed?

This is a basic 'C' question - nothing to do with Keil or ARM or microcontrollers.

I think you need to take a step back, get a good 'C' textbook, and work through learning the 'C' programming language on a PC before complicating the issue with embedded microcontrollers

Here are some 'C' learning & reference resources - including a free online textbook: blog.antronics.co.uk/.../

Andrew - I think, I have sth wrong wtih setting in Keil..let me explain.

First code (C online Compiler):

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

#define NULL '\0'

enum CompResult{DIFFERENT, EQUAL};

enum CompResult eCompareString(char pcStr1[], char pcStr2[]){

        unsigned char ucCounter;

        for(ucCounter=0; pcStr1[ucCounter]==pcStr2[ucCounter]; ucCounter++){
                if(pcStr1[ucCounter]==NULL){
                        return EQUAL;
                }
        }
        return DIFFERENT;
}
int main(){

        char pcStr1[] = {'a','b','c', NULL};
        char pcStr2[] = {'a','b','d', NULL};

    printf("Resullt: %d\n", eCompareString(pcStr1, pcStr2));

    return 0;

}

And result it's ok. It shows "1" when Strings are the same, otherwise show "0".

Second code (C++ online Compiler):

#include <iostream>
using namespace std;

#define NULL 0

enum CompResult{DIFFERENT, EQUAL};

enum CompResult eCompareString(char pcStr1[], char pcStr2[]){

        unsigned char ucCounter;

        for(ucCounter=0; pcStr1[ucCounter]==pcStr2[ucCounter]; ucCounter++){
                if(pcStr1[ucCounter]==NULL){
                        return EQUAL;
                }
        }
        return DIFFERENT;
}
int main(){

    char pcStr1[] = {'a','b','c', NULL};
    char pcStr2[] = {'a','b','d', NULL};

    cout << "Result: " << eCompareString(pcStr1, pcStr2) << endl;

    return 0;

}

Result above is the same. And here i got the code in Keil:

#include <LPC21xx.H>
#include <stdio.h>
#include <string.h>

#define NULL 0

enum CompResult{DIFFERENT, EQUAL};

enum CompResult eCompareString(char pcStr1[], char pcStr2[]){

        unsigned char ucCounter;

        for(ucCounter=0; pcStr1[ucCounter]==pcStr2[ucCounter]; ucCounter++){
                if(pcStr1[ucCounter]==NULL){
                        return EQUAL;
                }
        }
        return DIFFERENT;
}

int main(){

    char pcSource[] = {'a','b','c', NULL};
    char pcDestination[] = {'d','e','f', NULL};

    CopyString(pcSource, pcDestination);

    printf("Result: %d\n", eCompareString(pcStr1, pcStr2));

And when I click to debug (Ctrl + F5) then I can't deub my "main.c" program - it's happens always, when I use:

...
#include <stdio.h>
...
 printf("...", ...);
...