Memset in C++

In the C++ programming language, memset ( ) is a function used to fill memory blocks.

Initially, it converts the value of ‘ch‘ to the unsigned character. Here ‘ch’ refers to the character to be filled with another value passed in the memset ( ) function.
After then it copies the character ‘ch’ into each of the first ‘n’ characters of the object pointed by the st [ ].
Here the ‘n’ is referred to as the size of the block, which is mentioned in the memset ( ), and it must be equal or smaller with the size of the object pointed by st [ ].
If the value of n is greater than the size of the object pointed by the st [ ], it will generate error hence undefined.
If sometimes, a case arises where the object is not copyable, then also it will generate an error, and the behavior of the function is the same as in the previous case, i.e., undefined.
In the C++ programming language, the memset ( ) function is present in the < cstring > header file; without mentioning this header file, you would not be able to access the use of the memset ( ) function.
Here, the object which is not copy-able is as follows: array, C-compatible struct, scalar, and so on; hence the behavior of memset ( ) function is undefined in this case.
The only difference between the memset ( ) function and the memcpy ( ) function is that in memset ( ) function not only copies the value but replace it with the other substitute, e.g., if we want to replace each character of a particular string-like, ‘ cool ‘, with the alphabet ‘ f ‘, then; as a result, and it would be looking at final is; ‘ ffff ‘. But in memcpy ( ) function, it only copies the value from one place to another or copies a block of content from a particular place and puts it on another block of content.

Syntax of memset ( ) function:

Now, let us discuss the terminologies which are used here.

st [ ]: st [ ] represents the pointer to the memory required to be filled. It is a pointer to the object, where the character ‘ ch ‘ has been copied. As per the programmer’s choice, they can change the name from st to some other, depending on their need and work.
ch: ‘ ch ‘ here refers to the character, which is needed to be filled. It also varies from programmer to programmer choice, and they can rename it accordingly. It is converted to the unsigned char, whenever required and also it is converted into int format, but int acceptable values are only 0 and -1.
n: It denotes the size of the block, or can say it the numeric value which specifies the number of times the character ‘ ch ‘ needed to be copied and converted into the value passed in the memset ( ) function.

Advantages of memset ( ) function of C++

Increase readability: The memset ( ) function in C++ is mainly used to convert every character of the whole string into a particular int value which is passed as an input into the memset ( ) function. It is a one-line code; hence very short and ultimately increases the readability.
Reduce line of code: Instead of using unnecessary use of loops to assign and convert the value of each character present in the string with the int value, which is only passed as an input in this memset ( ) function, and the same task has been performed easily as compared with the lengthy method.
It is more Faster: Using the memset ( ) function is faster to convert each character of the given string into the value passed through an input, maybe of int type or any other, depending on the programmer. Its working is very fast rather than applying loops and while statements for performing the same task.
Useful in getting rid of Misalignment Problem: The memset ( ) function in C++ helps the programmer to get rid of misalignment problem. Sometimes, the case occurs where you find that you are dealing with the problem of misalignment of data in the processor, which leads to the error in the program. In this case, the memset ( ) and memcpy ( ) functions in C++ are the ultimate solutions of it.

Implementation of memset ( ) in C++

As we have already seen the concept of the memset ( ) function of C++ and its working, let us understand it in more detail with the help of an example.

Example 1:

  // Program to implement memset ( ) function in C++    #include   #include              // header file that contains the memset ( ) function, without it            // we cannot able to access the use of memset ( ) function  using namespace std ;    int main()  {  char st [ ] = ” tutoraspire ” ;  char ch ;  cout << ” Printing the given string : ” << st << endl ;  cout << ” Enter an alphabet from which you want to replace the each charater of the given string : ” ;  cin >> ch ;  memset ( st , ch , sizeof ( st ) ) ;  cout << ” Printing the string after replacing the each character of the string with the given substitute : ” << endl ;  cout << ” ” << st ;  return 0 ;  }  

The output of the above program:

In this above example, we have seen how each of the characters of the string ‘tutoraspire‘ has been converted into the single alphabet passed by a user. Here the space is also considered as a single character.

Example 2:

  // Program to implement memset ( ) function in C++    #include < iostream >  #include < cstring >             // header file that contains the memset ( ) function, without it //we cannot able to access the use of memset ( ) function   using namespace std ;  int main()  {  int arr [100] ;  int n , i , p ;  cout << ” Enter size of an integer array: ” ;   cin >> n ;  cout << ” Enter an array elements: ” << endl ;  for ( i = 0 ; i < n ; i++ )  {  cin >> arr [ i ] ;  }  cout << ” Printing the given array : ” << endl ;  for ( i = 0 ; i < n ; i++ )  {  cout << ” ” << arr [ i ] << endl ;  }  cout << ” Enter an integer value from which you want to replace the each charater of the given string : ” ;  cin >> p ;  memset ( arr , p , sizeof( arr ) ) ;  cout << ” Printing the array after replacing the each value of the array with the given substitute : ” << endl ;  for ( i = 0 ; i < n ; i++ )  {  cout << ” ” << arr [ i ] << endl ;  }    return 0 ;  }  

The output of the above program:

In this above example, we have seen how each of the characters of the string ‘tutoraspires’ has been converted into the integer value passed by a user. Here the space is also considered as a single character. Here the integer value only 0 and -1 is considerable, which implies that each character of the string is converted into the 0’s and -1’s only, instead of using other integer values, will result in a garbage value, which implies that if you have entered 2, then all the characters of the string has been replaced by a garbage value.

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Memset in C++

Memset in C++

Syntax of memset ( ) function:

Advantages of memset ( ) function of C++

Implementation of memset ( ) in C++

Example 1:

Example 2:

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