About C program(find memory content)

Question

Please, tell me what can i do... i am a beginner......i have no idea. please....

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1. Manually walk through the program.Write down the output that you expect will be displayed on screen.

2. Run the program Observe the result and check for any differences from your expectatation. Explain the difference(if any)

3.Complete the worksheet provide. this program is designed such that you can see the error happen. ignoring string length will either cause progrom crash or data couruption. The worst is that the system may not report any error.

4.Try solving this problem to complete the string copy operation eithout error.

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


int main(){

// This program is designed only for Visual C++ platform

char * source = "We are very bad",
      head[6] = "I am ",
      tail[5] ="good",
      destination[12];

printf("%s%s%s\n", "before string copy: ", head, tail);
strcpy(destination, source);     // copying between two other strings
                                 // not affecting head and tail

printf("%s%s%s\n", "after string copy: ", head, tail);

return 0;

}

(Above the quesion,I already solved the problem.( destination[12]; change to >>destination[18];)

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(i don't no how to finish this part) Brfore carrying out any modification to the program, trace the memory contents of all variables for following two statements (assume the statement has just been excuted).

A)     char* source="We are very bad",
       head[6]="good",
        destination[12];


memory Address Memory Content (hex value) Variable Name
                 _________________________ desination[12]
                 ___________________________ 
                 __________________________
                 ___________________________ 
                ____________________________ tail[5]
                 _____________________________ head[6]

B)        stropy(destination, source); //copying between two other strings
                  // not affecting head and tail


memory Address Memory Content (hex value) Variable Name
                  _________________________ desination[12]
                 ___________________________ 
                 __________________________
                 ___________________________ 
                ____________________________ tail[5]
                 _____________________________ head[6]

What is your observation?Is there anything can be done to improve the situation?

Observation:_________________________________

New C statement:____________________________

Answer 1

I suppose what this exercise is supposed to achieve is to teach you about buffer overflows. Three pointers:

• Count the number of characters inside the string source.
  (Side note: Don't forget to also count the implicit null character ('\0') which terminates the string.)

• Have a closer look at the destination buffer, especially note its capacity.

• Finally, given the knowledge you've just gathered, think about the consequences of doing a strcpy(destination, source).