malloc example in c

Example 1: how to use malloc in c

int* a =(int*)malloc(sizeof(int))

Example 2: how to use malloc in c

ptr = (castType*) malloc(size);

Example 3: malloc in c

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

    memoireAllouee = malloc(sizeof(int));
    if (string == NULL) 
    {
    	return;
   		string[0] = 'H';
        string[1] = 'e';
        string[2] = 'y';
        string[3] = '!';
        string[4] = '\0';
        printf("%s\n", string);
    }



    return 0;