On-board project Problem Solving

1 memset Function Solution

1. Void * memset (void * s, int C, size_t N)

Purpose: set the value of the first n Bytes of the memory space S to the value c.
2. Example # include
Void main () {char * s = "golden Global View ";
Clrscr ();
Memset (S, 'G', 6); printf ("% s", S );
Getchar (); Return 0;} 3. The memset () function is often used for memory space initialization. For example: Char STR [100]; memset (STR, 0,100 );
4. Deep connotation of memset:It is used to set all memory space to a specific character. It is generally used to initialize the defined string as ''or '/0'; Example: Char A [100]; memset (A, '/0', sizeof ());
Memcpy is used for memory copying. You can use it to copy any data type object and specify the length of the copied data. For example, char a [100], B [50]; memcpy (B, a, sizeof (B); note that if sizeof (a) is used, the memory address of B may overflow.
Strcpy can only copy strings. It ends copying when '/0' is encountered. For example, char a [100], B [50]; strcpy (A, B ); if strcpy (B, A) is used, check whether the length of the string in A (before the first '/0') exceeds 50 bits. If it exceeds, this will cause memory address overflow of B.
5. Supplement: memset can easily clear a variable or array of the structure type.
Example: struct sample_struct {char csname [16]; int iseq; int itype ;};
For the variable struct sample_strcut sttest;
Generally, sttest is cleared by sttest. csname [0] = '/0'; sttest. iseq = 0; sttest. itype = 0;
Memset (& sttest, 0, sizeof (struct sample_struct ));
If it is an array: struct sample_struct test [10]; then memset (test, 0, sizeof (struct sample_struct) * 10 );
6. Strcpy prototype: extern char * strcpy (char * DEST, char * SRC); usage: # I nclude function: copy the string of SRC ending with null to the array indicated by DeST. Note: The memory areas specified by Src and DEST cannot overlap and DEST must have sufficient space to accommodate SRC strings. Returns the pointer to DeST. Memcpy prototype: extern void * memcpy (void * DEST, void * SRC, unsigned int count); usage: # I nclude function: copy count bytes from the memory area indicated by Src to the memory area indicated by DeST. Note: the memory areas specified by Src and DEST cannot overlap. The function returns a pointer to DeST. Memset prototype: extern void * memset (void * buffer, int C, int count); usage: # I nclude function: set the first count bytes of the memory area referred to by buffer to the character C. Note: The pointer to the buffer is returned.

 

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On-board project Problem Solving