C + + Primer function Pass value 1

Don't look at C + + primer never know how bad their base is

There are generally two ways to pass values of functions: value passing, reference passing.

The value is passed in the following two ways:

void func (int a) {//}void func1 (int *a) {//}

Both Func and FUNC1 are implemented by copying memory.

Func1

int m = ten; func1 (int *a);//The process is: a = &m;  Then the M is indirectly manipulated by the pointer *a

Pass Reference

void Func2 (int &a) {//}

A reference is an alias of a variable, and no memory copy occurs.

A typical interview question:

void GetMemory1 (char *p) {    p = (char *) malloc (100);} void Test1 (void) {    char *str = NULL;    GetMemory1 (str);     strcpy (str, "Hello World");    printf (str);} <p></p><pre name= "code" class= "cpp" >//p = str;//p = malloc (...); Is there a half wool relationship between/p and str?

Char *getmemory2 (void) {char p[] = "Hello World"; return p;} void Test2 (void) {char *str = NULL; str = GetMemory2 (); printf (str);} Char *getmemory3 (void) {return "Hello World";} void Test3 (void) {char *str = NULL; str = GetMemory3 (); printf (str);} Hello world is printed in TEST3 because it returns a constant area and has not been altered. Hello world is not necessarily printed in Test2 because it points to a stack. void GetMemory4 (char **p, int num) {*p = (char *) malloc (num);} void Test4 (void) {char *str = NULL; GetMemory3 (&STR, 100); strcpy (str, "Hello"); printf (str);  }//memory does not release void Test5 (void) {char *str = (char *) malloc (*), strcpy (str, "Hello"), free (str), if (str! = NULL) {strcpy (str, "World"); printf (str); }}//STR is a wild pointer, the printed result is unknown void Test6 () {char *str= (char *) malloc (), strcpy (str, "Hello"); str+=6; free (str); if (str!=null {strcpy (str, "World"); printf (str);}} VC assertion failed, execution error

C + + Primer function Pass value 1