What is the use memset(), memcpy(), memmove() in C language?and memset(), memcpy(), memmove() example programs in c

memset()

Syntax:

#include <string.h>
void *memset( void *str, int ch, size_t n );

Description:
The function memset() copies ch into the first 'n' characters of str, and returns str. memset() is useful for intializing a section of memory to some value. For example:

memset(array, '\0', sizeof(array) );

it is a very efficient way to set all values of array to NULL.

memcpy()

Syntax:

#include <string.h>
void *memcpy( void *dest, const void *src, size_t n );

Description:
The function memcpy() copies 'n' characters from the array 'src' to the array 'dest'. memcpy() returns 'dest'. The behavior of memcpy() is undefined if 'src' and 'dest' overlap.

memmove()

Syntax:

#include <string.h>

void *memmove( void *dest, const void *src, size_t n );

Description:
The memmove() function is similer to |memcpy() function, except that it works even if 'src' and 'dest' memory areas overlap.

Example:

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

int main()
{

char temp[100];
char src[100]="hello world";
char dest[100];
char s[]="0123456789";
int i,len;

memset(temp,'\0',sizeof(temp));
printf("temp data after setting to NULL char\n");
for(i=0;i<100;i++)
    printf("%c ",temp[i]);
printf("\n");

memset(temp,56,sizeof(temp)-1);
printf("temp data after setting to 8(ascii value of 56)\n");
len = strlen(temp);
temp[len]='\0';
for(i=0;i<len;i++)
    printf("%d ",temp[i]);//printing integer values

printf("\n");
printf("temp:%s\n",temp);// printing acsii values

memcpy(dest,src,sizeof(src));
printf("Data in dest after memcpy %s\n",dest);

memmove(dest,"world",5);
printf("Data in dest after memmove %s\n",dest);

return 0;
}
Output:
temp data after setting to NULL char
                                                                                                   
temp data after setting to 8(ascii value of 56)
56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56 56
temp:888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888
Data in dest after memcpy hello world
Data in dest after memmove world world