C

malloc in c

#include <stdlib.h>

void *malloc(size_t size);

void exemple(void)
{
  char *string;
  
  string = malloc(sizeof(char) * 5);
  if (string == NULL)
    return;
  string[0] = 'H';
  string[1] = 'e';
  string[2] = 'y';
  string[3] = '!';
  string[4] = '';
  printf("%s
", string);
  free(string);
}

/// output : "Hey!"

what does malloc do

adds specified amount of memory but there could be more writable memory ahead, so you have to decide how much you access

C malloc

#include <stdlib.h>
int main(){
int *ptr;
ptr = malloc(15 * sizeof(*ptr)); /* a block of 15 integers */
    if (ptr != NULL) {
      *(ptr + 5) = 480; /* assign 480 to sixth integer */
      printf("Value of the 6th integer is %d",*(ptr + 5));
    }
}

C malloc

Example: ptr = (int *) malloc (50)

malloc basics

// Program to calculate the sum of n numbers entered by the user

#include <stdio.h>
#include <stdlib.h>

int main() {
  int n, i, *ptr, sum = 0;

  printf("Enter number of elements: ");
  scanf("%d", &n);

  ptr = (int*) malloc(n * sizeof(int));
 
  // if memory cannot be allocated
  if(ptr == NULL) {
    printf("Error! memory not allocated.");
    exit(0);
  }

  printf("Enter elements: ");
  for(i = 0; i < n; ++i) {
    scanf("%d", ptr + i);
    sum += *(ptr + i);
  }

  printf("Sum = %d", sum);
  
  // deallocating the memory
  free(ptr);

  return 0;
}

malloc

// if you initialize a pointer and want to use it like an array, 
// you have to claim the space you use, 
// that is what the memory-allocation-funtion (malloc) does;

// exaple for that: str(0) belongs to you, but str(1), str(2), ... do not
// if you do not use the malloc funtion; 
// you can access it, but it could be used by another programm;

#include <stdio.h>
#include <stdlib.h>

void func(void)
{
    char *str = malloc(sizeof(char) * 5); // sizeof --> char needs 
    // a specific space per value saved;
    // *5 --> 5 is the number of values in the array;

    char *str1 = malloc( 5 * sizeof *str1 );//      |
    char *str2 = malloc( sizeof(char[5]) );//       | other syntaxes

    if(str == NULL) { exit(1); } // malloc returns NULL 
    // if it could not allocate the memory;
    str[0] = 'H';
    *(str+1) = 'e';	// used like pointer
    str[2] = 'y';	// used like array
    *(str+3) = '!';
    str[4] = '';

    printf("%s
", str);

    free(str); // frees the memory allocated to str;
    // if you free the memory too early and try to access str later
    // that is called a memory leak;
}

int main(void)
{
    func();
    return 0;
}

// shell: Hey!

// improved version of Thurger's

malloc in c

// Let's allocate enough space on the heap for an array storing 4 ints

intArray = (int *) malloc(4 * sizeof(int)); // A pointer to an array of ints

intArray[0] = 10;
intArray[1] = 20;
intArray[2] = 25;
intArray[3] = 35;

malloc c

int main(int argc, char *argv[])
{
    int* memoireAllouee = NULL;

    memoireAllouee = malloc(sizeof(int));
    if (memoireAllouee == NULL) // Si l'allocation a échoué
    {
        exit(0); // On arrête immédiatement le programme
    }

    // On peut continuer le programme normalement sinon

    return 0;
}

malloc

/*
 *Dynamic memory creation using malloc
 *Language: C
 */

#include<stdio.h>
//To use malloc function in our program
#include<stdlib.h>

int main()
{
    int *ptr;

    //allocating memory for 1 integer
    ptr = malloc(sizeof(int));

    if(ptr != NULL)
           printf("Memory created successfully
");

    return 0;
}

malloc

#include <stdio.h>
#include <stdlib.h>

char *create_array(unsigned int, char);

/**
 * main - check the code .
 *
 * Return: Always 0.
 */
int main(void)
{
	char *buffer;
	unsigned int size;

	size = 0;
	buffer = create_array(size, 'H');
	if (buffer == NULL)
	{
		printf("failed to allocate memory
");
		return (1);
	}
	free(buffer);
	return (0);
}

Malloc

ptr = malloc(size); //You dont need to cast

C malloc

ptr = (cast_type *) malloc (byte_size);

malloc

char *ptr;
ptr = malloc(10);

c malloc

int cp(void)
{
    char *s;

    s = malloc(12);
    strcpy(s, "Best School");
    return (0);
}