How do I receive a string from a function correctly?

Question

0.00/5 (No votes)

See more:

Good morning

I wonder how to fix my program so that it copies array A to array A2 in the function "copyarraystringto()" and returns the A2 string to the function printf() which should display the string in array A2?

// Jones, Bradley L.; Peter Aitken; Dean Miller. C Programming in One Hour a Day, Sams Teach Yourself (pp. 400). Pearson Education. Kindle Edition.
//
/* Exercise 5, lesson 10.  */

  #include <stdio.h>

  char A[18] = { "Pointers are fun!" };
  char A2[18];

  char copyarraystringto(char Ac[], char A2c[]);

  int main( void )
  {

     printf("%s", copyarraystringto(A, A2));

     return 0;
 }

char copyarraystringto(char Ac[], char A2c[])
{

    strcpy(A2, A);

    return A2;
}

What I have tried:

I have tried to use the "Debug" in CodeBlocks 20.03 and there was a problem in this line:

printf("%s", copyarraystringto(A, A2));

. Something about memory. This info from CodeBlocks:

Cannot access memory at address 0x0

.

Posted 5-Sep-21 23:51pm

Mieczyslaw1683

Updated 6-Sep-21 7:30am

Add a Solution

3 solutions

Solution 2

In my opinion, that should be:

C

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


int main()
{
  char source[] = { "Pointers are fun!" };
  char target[sizeof(source)];

  printf( "%s\n", strncpy(target, source, sizeof(source)));

  return 0;
}

Posted 6-Sep-21 0:55am

CPallini

Solution 3

In C your are responsible for memory managment and so you should do with functions. A simple example

C++

char* createString() {
  char *s = malloc(/*some size*/);
  // do stuff
  return s;
}
// usage
char *text = createString();
// do further stuff
  free( text );

hint: I use create WHEN allocating memory, so the callee knows that free is his job.

Posted 6-Sep-21 7:30am

KarstenK

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2021-09-06T00:21:00

First off, that won't compile because copyarraystringto returns a char rather than a pointer.

char *copyarraystringto(char Ac[], char A2c[])

You pass parameters to your function:

char copyarraystringto(char Ac[], char A2c[]);
...
printf("%s", copyarraystringto(A, A2));

But you don't use them:

char copyarraystringto(char Ac[], char A2c[])
{

    strcpy(A2, A);

    return A2;
}

So you copy the empty global string A2 into the full global string A and then return it - so you print an empty string.

Use the parameters instead:

char *copyarraystringto(char Ac[], char A2c[])
{

    strcpy(A2c, Ac);

    return A2c;
}

And it'll work.

But please, use sensible variable names! It makes code a lot easier to read and work with later...

char copyarraystringto(char source[], char dest[])
{

    strcpy(source, dest);

    return dest;
}