memcpy() in C

Introduction: Here we discuss about the memcpy() function in C. The memcpy() function is also called the Copy Memory Block function. Used to create a copy of a specific drawing area. This function can copy objects from one memory block to another only if the two objects do not overlap at any point.

Implementing the memcpy() function in the C programming language is relatively simple. The logic behind the memcpy() function is elementary.

To implement the memcpy() function, you must cast the source and destination addresses to char*(1 byte). After the type conversion is complete, copy the contents from the source array to the destination address.

You have to split the data by bytes. Repeat this step until n units are completed. where n is the specified bytes of data to copy.

The syntax of the memcpy() function in C: The syntax of the memcpy() function in C is given below

void *memcpy(void *arr1, const void *arr2, size_t n);  

The memcpy() function copies the specified n characters from the source array or location. In this case, arr1 to the destination, which is arr2. Both arr1 and arr2 are pointers to the source and destination locations, respectively.

Parameter of the memcpy() function in C: There are three parameters of the memcpy() function in C. These are-

arr1: This is the first parameter of the function specifying the location of the source memory block. This represents the array that will be copied to the destination.

 arr2: The second parameter of the function specifies the location of the target memory block. This represents the destination array of the memory block.

n: Specifies the number of characters copied from the source to the destination.

Return value of the memcpy() function in C:

The memcpy() function in C is return some value. Returns the pointer that is arr1.

Header file of the memcpy() function in C: The memcpy() function is defined in the string.h header file and must be included in the code that implements the function.

#include <string.h>

Example 1: Here we give an example of the memcpy() function in C.

#include <stdio.h>
#include <string.h>
Int main()
{
const char src[50] = “Tutorial and examples”;
char dest[50];
strcpy (dest, “Hello!”);
printf(“Before memcpy dest= %s\n”, dest);
memcpy(dest, src, strlen(src)+1);
printf(“After memcpy dest = %s\n”, dest);
return 0;
}	

Result: We compile the above program and also share the output of it. The result is given below:

Before memcpy dest= Hello!
After memcpy dest = Tutorial and examples

Example 2: Here we give another example of the memcpy() function in C.

#include <stdio.h>
#include <string.h>
Int main()
{
char str1[] = “Tree”;
char str2[] = “Flower”;
puts(“str1 before memcpy”);
puts(str1);
memcpy (str1, str2, sizeof(str2));
puts(“\nstr1 after memcpy”);
puts(str1);
return 0;
}

Result: We compile the above program and also share the output of it. The result is given below:

str1 before memcpy
Tree
str1 after memcpy
Flower

Example 3: Here we give another example of the memcpy() function in C.

#include <stdio.h>  
#include <string.h>  
int main()  
{  
//initialize the source array,  
//the data will be copied from source to destination/  
int sourcearr[100] = {1,2,3,4,5};  
//this is the destination array  
//data will be copied at this location.  
int destarr[100] = {0};  
//copy the data stored in the sourcearr buffer into destarr buffer  
memcpy(destarr,sourcearr,sizeof(sourcearr));  
//print the data copied into destarr  
printf("destination array content is now changed to\n");  
for(int i=0;i<5;i++){  
printf("%d", destarr[i]);  
}
return 0;
}  

Result: We compile the above program and also share the output of it. The result is given below:

 destination array content is now changed to 12345

Example 4: Here we give another example of the memcpy() function in C.

#include <stdio.h>  
#include <string.h>  
struct  
{  
char name[40];  
int age;  
} prsn1, prsn2;  
int main()  
{  
char firstname[]="Rudra";  
//Using the memcpy() function to copy the data from  
//firstname to the struct  
//add it is as prsn1 name  
memcpy ( prsn1.name, firstname, strlen(firstname)+1 );  
//initialize the age of the prsn1  
prsn1.age=23;  
//using the memcpy () function to copy one person to another  
//the data will be copied from prsn1 to prsn2  
memcpy ( &prsn2, &prsn1, sizeof(prsn1) );  
//print the stored data  
//display the value stored after copying the data  
//from prsn1 to prsn2  
printf ("person2: %s, %d \n", prsn2.name, prsn2.age );  
return 0;  
}  

Result: We compile the above program and also share the output of it. The result is given below:

person2: Rudra, 23