C++ memset() is an inbuilt function that is used to copy the character to a memory block for n number of times to an object. In simpler words, it is used to fill the memory block with a particular value. It converts the value ch to unsigned char and copies it into each of the first n characters of the object pointed to by str[].
C++ memset()
The memset() function in C++ copies a single character for a specified number of time to an object.
Syntax
void* memset(void* str_var, int char_var, size_t num)
It basically converts the char_var to unsigned char datatype and copies the first num characters of the object which is pointed by str_var.
memset() can also be used to assign integer value 0 and -1 to some array. It is strictly restricted to 0 and 1 setting other values won’t work.
Parameters
It takes 3 parameters. First is str_var which is a pointer to the string object.
Second is char_var which is the character we want to copy and third is num which indicates the number of bytes we want to copy.
Return Value
It returns the str_var which is the pointer to the final output string.
Example programs on memset() function in C++
Example 1: Write a program to show the working of the memset() function.
#include <iostream>
#include <string.h>
using namespace std;
int main()
{
char str_var[] = "HelloWorldIamTheBoss";
memset(str_var, 'q', sizeof(str_var));
cout << str_var;
return (0);
}
Output
qqqqqqqqqqqqqqqqqqqq
Example 2: Write a program to set -1 to all the array elements using memset() function.
#include <iostream>
#include <string.h>
using namespace std;
int main()
{
int arr[10];
memset(arr, -1, sizeof(arr));
for (int i = 0; i < 10; i++)
{
cout << arr[i];
}
return (0);
}
Output
-1-1-1-1-1-1-1-1-1-1
We can use memset() to set all values as 0 or -1 for integral data types also. It will not work if we use it to set other values. The reason is simple: memset() works byte by byte.
