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Some usage of sizeof

Discussion in 'C' started by wdliming, Jan 1, 2011.

  1. wdliming

    wdliming New Member

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    Code:
    #include<stdio.h>
    #include<string.h>
    char foo()
    {
    	printf("foo() has been called.\n");
    	return 'a';
    }
    /*void foo3(char a3[3])
    {
    	int c3 = sizeof( a3 ); // c3 == 
    	printf("c3=sizeof( a3 )=%d\n",c3);
    }
    void foo4(char a4[])
    {
    	int c4 = sizeof( a4 ); // c4 == 
    	printf("c4=sizeof( a4 )=%d\n",c4);
    }*/
    
    /*mian function*/
    int main()
    {
    	int n;
    	n = 10; 
    	char ary[n];		   
    	printf("sizeof(ary)       =%d\n", sizeof(ary)); // ok. output: 10
    	
    	size_t sz = sizeof( foo() );	// The type return value of the foo()is char,
    									//besides sz=sizeof(char),foo()Will not be called
    	printf("sizeof( foo() )   =%d\n", sz);
    	
    	/*****************************Data Type*****************************************************/
    	printf("sizeof(char)         =%d\n",sizeof(char));
    	printf("sizeof(signed char)  =%d\n",sizeof(signed char));
    	printf("sizeof(unsigned char)=%d\n",sizeof(unsigned char));
    	printf("sizeof(int)          =%d\n",sizeof(int));
    	printf("sizeof(signed int)   =%d\n",sizeof(signed int));
    	printf("sizeof(unsigned int) =%d\n",sizeof(unsigned int));
    	printf("sizeof(float)        =%d\n",sizeof(float));
    	printf("sizeof(double)       =%d\n",sizeof(double));
    	
    	/******************************point**********************************************************/
    	char *pc = "abc";
    	int *pi;
    	//string * ps;
    	char **ppc = &pc;
    	void (*pf)();// 
    	printf("sizeof(pc)          =%d\n",sizeof(pc)); //4
    	printf("sizeof(pi)          =%d\n",sizeof(pi)); //4
    	//sizeof( ps ); // 
    	printf("sizeof(ppc)         =%d\n",sizeof(ppc)); //4
    	printf("sizeof(pf)          =%d\n",sizeof(pf));// 4
    	
       /***********************Array*****************************************************************/ 
    	char a1[] = "abc";
    	int a2[3];
    	printf("sizeof(a1[])     =%d\n",sizeof(a1));// 4
    	
    	printf("sizeof(a2[])     =%d\n",sizeof(a2[3]));//3*4=12(attach to int)
    	
    	/*Calculate the numbers of the array*/
    	
    	int c1; //  Total length / length of a single element
    	printf("c1= sizeof( a1 ) / sizeof(char) =%d\n",c1= sizeof( a1 ) / sizeof( char )); 
    	int c2;//   Total length / length of the first element
    	printf("c2= sizeof( a1 ) / sizeof(a1[0])=%d\n",c2 = sizeof( a1 ) / sizeof( a1[0] ));
    	//printf("c4=sizeof( a2 )=%d\n",foo4(a2));
    	
    	/******************************Structure*****************************************************/
    	struct S1
    	{
    		char c;
    		int i;
    	};
    	printf("sizeof(S1)=%d\n",sizeof(struct S1));
    	struct S2
    	{
    		int i;
    		char c;
    	};
    	printf("sizeof(S2)=%d\n",sizeof(struct S2));
    	struct S3
    	{
    		char c1;
    		S1 s;
    		char c2;
    	};
    	printf("sizeof(S3)=%d\n",sizeof(struct S3));
    	
    	/*************************************Bit field****************************************************/
    	struct BF1
    	{
    		char f1 : 3;
    		char f2 : 4;
    		char f3 : 5;
    	};
    	printf("sizeof(BF1)=%d\n",sizeof(struct BF1));
    	union U
    	{
    		int i;
    		char c;
    		S1 s;
    	};
    	printf("sizeof(U)=%d\n",sizeof(U));
    	return 0;
    }
    Welcome to give some constructive suggestions!
    Thank you!
     
    Last edited by a moderator: Jan 2, 2011
  2. xpi0t0s

    xpi0t0s Mentor

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    Please use code tags when posting code. It preserves the formatting.

    Also please read the posting guidelines.
     
  3. shabbir

    shabbir Administrator Staff Member

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    As of Now I have done it for you and so read the link in the reasons about what is code blocks and how you can use them
     

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