C: Using realloc() To Resize An Array Of Ints.
https://github.com/pereiradaniel/c_programs/blob/master/dyn_mem/realloc/realloc.c
// Dynamic Memory Allocation - realloc
// -----------------------------------
// This program accepts user input to create a dynamic array of ints.
// calloc zeroes the space first!
#include <stdio.h>
#include <stdlib.h> // calloc!
int main(int argc, char* argv[])
{
// Prompt user for number of ints for dynamic memory allocation:
int num_ints = 0;
printf("This program will dynamically allocate memory for an array of ints.\nHow many ints would you like? ");
scanf(" %d", &num_ints);
// Create a dynamically allocated array of integers using user input:
int *a = calloc(num_ints, sizeof(int));
// Displays zeroed data first:
printf("Using calloc zeroes all the data first:\n");
for (int i=0; i<num_ints; ++i)
printf("a[%d] = %d\n", i, a[i]);
printf("\n"); // new line!
// Use for loop to assign values to the int array a.
for (int i=0; i<num_ints; ++i)
a[i] = i;
// Use for loop to print contents of array a.
printf("After the ints have been assigned:\n");
for (int i=0; i<num_ints; ++i)
printf("a[%d] = %d\n", i, a[i]);
printf("\n"); // new line!
printf("a: %p\n", a); // Prints memory location of a.
printf("Resizing a...\n");
a = realloc(a, sizeof(int) * (num_ints + 5)); // Resize a.
// Set new memory locations to value of 9
for (int i=num_ints; i<(num_ints+5); ++i)
a[i] = 9;
printf("\n"); // new line!
printf("After the array has been resized (new spaces filled with 9):\n");
for (int i=0; i<(num_ints+5); ++i)
printf("a[%d] = %d\n", i, a[i]);
printf("\n"); // new line!
// int *save = a; // Save memory location to ptr a!
free(a); // Deallocate memory!
return 0;
}==273== Memcheck, a memory error detector ==273== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==273== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info ==273== Command: ./realloc ==273== This program will dynamically allocate memory for an array of ints. How many ints would you like? 5 Using calloc zeroes all the data first: a[0] = 0 a[1] = 0 a[2] = 0 a[3] = 0 a[4] = 0 After the ints have been assigned: a[0] = 0 a[1] = 1 a[2] = 2 a[3] = 3 a[4] = 4 a: 0x4a4e8c0 Resizing a... After the array has been resized (new spaces filled with 9): a[0] = 0 a[1] = 1 a[2] = 2 a[3] = 3 a[4] = 4 a[5] = 9 a[6] = 9 a[7] = 9 a[8] = 9 a[9] = 9 ==273== ==273== HEAP SUMMARY: ==273== in use at exit: 0 bytes in 0 blocks ==273== total heap usage: 4 allocs, 4 frees, 2,108 bytes allocated ==273== ==273== All heap blocks were freed -- no leaks are possible ==273== ==273== For lists of detected and suppressed errors, rerun with: -s ==273== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
