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What is a free function in C++?
The C/C++ library function void free(void *ptr) deallocates the memory previously allocated by a call to calloc, malloc, or realloc. Following is the declaration for free() function.
void free(void *ptr)
This function takes a pointer ptr. This is the pointer to a memory block previously allocated with malloc, calloc or realloc to be deallocated. If a null pointer is passed as argument, no action occurs.
Example
#include <iostream> #include <cstdlib> #include <cstring> using namespace std; int main () { char *str; /* Initial memory allocation */ str = (char *) malloc(15); strcpy(str, "tutorialspoint"); cout << "String = "<< str <<", Address = "<< &str << endl; /* Reallocating memory */ str = (char *) realloc(str, 25); strcat(str, ".com"); cout << "String = "<< str <<", Address = "<< &str << endl; /* Deallocate allocated memory */ free(str); return(0); }
Output
String = tutorialspoint, Address = 0x22fe38 String = tutorialspoint.com, Address = 0x22fe38
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