<string.h> header functions (2) - Copy and Concatenate

Copy and Concatenate Funtion

strcpy : Copy string

char* strcpy(char* destination, const char* source);

destination : Pointer to the destination array where the content is to be copied.

source : C string to be copied.

Return Value

• destination is returned

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

int main ()
{
  char str1[]="Sample string";
  char str2[40];
  char str3[40];
  strcpy (str2,str1);
  strcpy (str3,"copy successful");
  printf ("str1: %s\nstr2: %s\nstr3: %s\n",str1,str2,str3);
  return 0;
}

str1: Sample string
str2: Sample string
str3: copy successful

---

strncpy : Copy characters from string

char* strncpy(char* destination, const char* source, size_t num);

destination : Pointer to the destination array where the content is to be copied.

source : C string to be copied.

num : Maximum number of characters to be copied from source.

Return Value

• destination is returned.

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

int main ()
{
  char str1[]= "To be or not to be";
  char str2[40];
  char str3[40];

  strncpy ( str2, str1, sizeof(str2) );

  strncpy ( str3, str2, 5 );
  str3[5] = '\0';   /* null character manually added */

  puts (str1);
  puts (str2);
  puts (str3);

  return 0;
}

To be or not to be
To be or not to be
To be

---

strcat : Concatenate strings

char* strcat(char* destination, const char* source);

destination : Pointer to the destination array, which should contain a C string, and be large enough to contian the concatenated resulting string.

source : C string to be appended. This should not overlap destination.

Return Value

• destination is returned.

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

int main ()
{
  char str[80];
  strcpy (str,"these ");
  strcat (str,"strings ");
  strcat (str,"are ");
  strcat (str,"concatenated.");
  puts (str);
  return 0;
}

these strings are concatenated. 

---

strncat : Append characters from string

char* strncat(char* destination, const char* source, size_t num);

destination : Pointer to the destination array, which should contain a C string, and be large enough to contain the concatenated resulting string, including the additional null-character.

source : C string to be appended.

num : Maximum number of characters to be appended.

Return Value

• destination is returned.

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

int main ()
{
  char str1[20];
  char str2[20];
  strcpy (str1,"To be ");
  strcpy (str2,"or not to be");
  strncat (str1, str2, 6);
  puts (str1);
  return 0;
}

To be or not