C - Write calloc, by calling malloc or by modifying it

怼烎@ 2023-01-13 06:28 134阅读 0赞

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/*
     * The standard library function calloc(n,size) returns a pointer to n objects of
     * size size, with the storage initialized to zero.
     * Write calloc, by calling malloc or by modifying it.
     *
     * CAlloc.c - by FreeMan
     */
    
    #include <stdlib.h>
    #include <string.h>
    
    void *mycalloc(size_t nmemb, size_t size)
    {
    	void *Result = NULL;
    
    	/* use malloc to get the memory */
    	Result = malloc(nmemb * size);
    
    	/* and clear the memory on successful allocation */
    	if (NULL != Result)
    	{
    		memset(Result, 0x00, nmemb * size);
    	}
    
    	/* and return the result */
    	return Result;
    }
    
    #include <stdio.h>
    
    int main(void)
    {
    	int *p = NULL;
    	int i = 0;
    
    	p = mycalloc(100, sizeof * p);
    	if (NULL == p)
    	{
    		printf("mycalloc returned NULL.\n");
    	}
    	else
    	{
    		for (i = 0; i < 100; i++)
    		{
    			printf("%08X ", p[i]);
    			if (i % 8 == 7)
    			{
    				printf("\n");
    			}
    		}
    		printf("\n");
    		free(p);
    	}
    
    	return 0;
    }
    
    // Output:
    /*
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    00000000 00000000 00000000 00000000
    
    */

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