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The strcpy() is a string manipulation function defined in the cstring header file, which works on a string which is stored in a c-style char array and this function is used copy the characters of one string to another string.

• Signature of strcpy() function




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




• A source is a string passed to this function, whose characters are to be copied to another string destination.
• This function copies the characters of source string to another string destination and returns a char[] array pointer, pointing to the destination string.







• Example of strcpy() function


In the upcoming code, we are calling strcpy() function, to copy the content of one string contained in a char[] array named src to another string contained in the second char[] array named dest, both string values are passed as a parameter to the strcpy() function.



// strncpy example 

#include<iostream>
#include<cstring>

using namespace std;

int main()
{
char src[10] = "Welcome";
char dest[10];

cout<< "The content of source string : " << src << "\n";
strcpy(dest, src);

cout<< "Copying the string is completed" << "\n";
cout<< "The content of source string : " << src << "\n";
cout<< "The content of destination string : " << dest;

return 0;
}





Output is -




The content of source string : Welcome
Copying the string is completed
The content of source string : Welcome
The content of destination string : Welcome



• The first char[] array i.e. src is initialized with a string value Welcome and the second char[] array i.e. dest is not initialized with any value.
• The function strcpy() copies the string value in the src char[] array in the second char[] array i.e. dest, when both char[] arrays are passed as parameter to strcpy() function.







• Another example of strcpy() function


In the upcoming code, we are calling strcpy() function, to copy the content of one string named src to another string named dest, while overwriting its content. Both string values are contained in a char[] array and are passed as a parameter to the strcpy() function.



// strncpy example 

#include<iostream>
#include<cstring>

using namespace std;

int main()
{
char src[30] = "Be good to each other";
char dest[30] = "Hello";

cout<<"The content of source string : " <<src <<"\n";
strcpy(dest, src);

cout<<"Copying the string is completed" <<"\n";
cout<<"The content of source string : " <<src <<"\n";
cout<<"The content of target string : " <<dest;

return 0;
}





Output is -




The content of source string : Be good to each other
Copying the string is completed
The content of source string : Be good to each other
The content of target string : Be good to each other



• The first char[] array i.e. src is initialized with a string value Be good to each other and the second char[] array i.e. dest is not initialized with any value.
• The function strcpy() copies the string value in the src char[] array in the second char[] array i.e. dest, when both char[] arrays are passed as parameter to strcpy() function.





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• Copying one string to another without using strcpy() function

Let's create a program which copies the characters in one string to another string without using strcpy() function.

// Program to copy the characters of one string to another string without using strcpy()

#include<iostream>
#include<cstring>

using namespace std;

int main()
{
char dest[20] = "Blue";
char src[10] = "Skies";

cout<< "The value in dest string : " << dest << "\n";

cout<< "The second in src string : " << src << "\n";

int len1 = strlen(dest);
int len2 = strlen(src);

cout<< "Length of characters in dest string : " << len1 << "\n";
cout<< "Length of characters in src string : " << len2 << "\n";

int i; 
for(i=0;i<len2; i++)
{
	dest[i] = src[i];
	len1 = len1 + 1 ;
}

// appending null-character at the end of dest char array when copying finishes 
dest[i]='\0'; 


cout<< "Copying src string into dest is done" << "\n";
cout<< "The value in dest string : " << dest << "\n";
cout<< "The second in src string : " << src;

return 0;
}

Output is :

The value in dest string : Blue
The second in src string : Skies
Length of characters in dest string : 4
Length of characters in src string : 5
Copying src string into dest is done
The value in dest string : Skies
The second in src string : Skies

• The first char[] array i.e. dest is initialized with a string value Blue and the second char[] array i.e. src is initialized with the value Skies.
• Next, we have calculated the total length of characters actually present in each char[] array, by using strlen() function.
• Next, we have manually copied each character from src char[] array to dest char[] and at the end of copying the characters, we have also added a null character i.e. '\0' at the end of dest char[] array to mark its end.

Note: - The function strlen returns the total number of characters actually present in the char[] and not the total number of character it can hold.

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C++ strncpy() function >

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