华中科技大学博士论文答辩会-M.MuNeeBReHmaN.ppt

Pointers to Pointers C++ allows the use of pointers that point to pointers, that these, in its turn, point to data (or even to other pointers). char a; char *b; char **c; a = z; b = a; c = b; cout**c; Pointer to string constant Syntax: char * string Literal void main() { char str1[] = “Defined as an array”; char* str2 = “Defined as a pointer”; cout str1 endl; cout str2 endl; //str1++; // can’t do this; str1 is a constant str2++; // this is ok, str2 is a pointer cout str2 endl; // efined as a pointer } Pointer to string constant // Copying string using Pointers void main() { char* str1 = “Self-conquest is the greatest victory.”; char str2[80]; //empty string char* src = str1; char* dest = str2; while( *src ) //until null character, *dest++ = *src++; //copy chars from src to dest *dest = ‘\0’; //terminate dest cout str2 endl; //display str2 } Computer Programming Computer Programming Pointers Objectives To describe what a pointer is To learn how to declare a pointer and assign a value to it To access elements via pointers To pass arguments by reference with pointers To understand the relationship between arrays and pointers To know how to access array elements using pointers To declare constant pointers and constant data Introduction to Pointers Pointer variables, simply called pointers, are designed to hold memory addresses as their values Normally, a variable contains a specific value, e.g., an integer, a floating-point value, and a character However, a pointer contains the memory address of a variable that in turn contains a specific value Introducing Pointers When we declare a variable, some memory is allocated for it. Thus, we have two properties for any variable: Its Address and Its Data value For Example, int count = 5; Introducing Pointers How to get the memory-address of a variable? Address of a variable can be accessed thr