C++ strcpy()

#include <cstring>
#include <iostream>

using namespace std;

int main() {
  char src[] = "Hello Programmers.";
    
  // large enough to store content of src
  char dest[20];

  // copy the contents of src to dest    
  strcpy(dest,src);
  
  cout << dest;

  return 0;
}

// Output: Hello Programmers.

strcpy() Syntax

The syntax of strcpy() is:

strcpy( char* dest, const char* src );

strcpy() Parameters

The strcpy() function takes the following parameters:

• dest - pointer to a C-string where the contents are copied to
• src - pointer to a C-string where the contents are copied from

strcpy() Return Value

The strcpy() function returns:

• dest (the pointer to the destination C-string)

strcpy() Prototype

The prototype of strcpy() as defined in the cstring header file is:

char* strcpy(char* dest, const char* src);

The strcpy() function copies the C-string pointed to by src to the memory location pointed to by dest. The null terminating character '\0' is also copied.

Notice that:

• src is of const char* type. The const keyword ensures that the C-string pointed to by src cannot be modified by strcpy().
• dest is of char* type. The absence of const ensures that the C-string pointed to by dest can be modified by strcpy().

strcpy() Undefined Behavior

The behaviour of strcpy() is undefined if:

• The memory allocated for dest pointer is not large enough.
• The strings overlap.

Example: C++ strcpy()

#include <cstring>
#include <iostream>

using namespace std;

int main() {
  char src[20] = "I am the source.";

  // large enough to store content of src
  char dest[30] = "I am the destination.";
    
  cout << "dest[] before copy: " << dest << endl;

  // copy contents of src to dest    
  strcpy(dest,src);

  cout << "dest[] after copy: " << dest;

  return 0;
}

Output

dest[] before copy: I am the destination.
dest[] after copy: I am the source.