What's problem with this program?

This is a discussion on What's problem with this program? within the Linux Programming forums, part of the Platform Specific Boards category; //it calculates the number of space/tab/enter key of the string you input from the keybord. But when I run it ...

  1. #1
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    Jun 2010
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    What's problem with this program?

    //it calculates the number of space/tab/enter key of the string you input from the keybord. But when I run it and input the string with "CTRL-Z" to end, nothing display on the dos screen. why??
    Code:
     
    #include<stdio.h>
    #include <string.h>
    int main()
    {
    	char c;
    	int space=0,table=0,enter=0;
    	printf("please input a string:\n");
    	scanf("%c",&c);
    	while(c!=(char)EOF)
    	{
    		switch(c)
    		{
    			case 32:space++;break;	
    			case 9:table++;break;
    			case 10:enter++;break;
    			default : break;
    		}
    	    scanf("%c",&c);
    	}
    	
    	printf("the number of space:%d\n",space);
    	printf("the number of table:%d\n",table);
    	printf("the number of enter:%d\n",enter);
    
    	getchar();
    	return 0;
    }

  2. #2
    spurious conceit MK27's Avatar
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    1) it's not a "dos" screen, it's the bash shell. You don't signal EOF with ctrl-Z, you signal it with ctrl-D.

    However, EOF is not really a char value, it's an int. Read this:
    C file input/output - Wikipedia, the free encyclopedia
    Which exactly describes your problem. Unfortunately, it does not exactly describe a solution for scanf(), because using scanf("%c") to read into an int will not produce very satisfactory results. You need to use getchar() or fgetc().

    You can also use fgets(), which handles EOF properly:
    Code:
    #include<stdio.h>
    #include <string.h>
    int main()
    {
    	char line[4096];
    	int len, i, space=0,table=0,enter=0;
    	printf("please input a string:\n");
    	while(fgets(line,4096,stdin)) {
    		len = strlen(line);
    		for (i=0;i<len;i++) {
    			switch(line[i]) {
    				case 32:space++;break;	
    				case 9:table++;break;
    				case 10:enter++;break;
    				default : break;
    			}
    		}
    	}
    	
    	printf("the number of space:%d\n",space);
    	printf("the number of table:%d\n",table);
    	printf("the number of enter:%d\n",enter);
    
    	/* no MS IDE, no final getchar */
    	return 0;
    }
    However, you might sometimes have to hit ctrl-D twice.

    The best way to do this is with getchar or fgetc.
    Last edited by MK27; 06-23-2010 at 08:38 AM.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  3. #3
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    Yeah!It is working now.But I want to run it in VB, then I did try . However, it is a pity that it didn't work.Why?

  4. #4
    Registered User jeffcobb's Avatar
    Join Date
    Dec 2009
    Location
    Henderson, NV
    Posts
    875
    Quote Originally Posted by Steve Cao View Post
    Yeah!It is working now.But I want to run it in VB, then I did try . However, it is a pity that it didn't work.Why?
    You do know this is the Linux subforum right?? Like VB doesn't run here....so how did you expect it to work?
    C/C++ Environment: GNU CC/Emacs
    Make system: CMake
    Debuggers: Valgrind/GDB

  5. #5
    CSharpener vart's Avatar
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    Rishon LeZion, Israel
    Posts
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    Code:
    				case 32:space++;break;	
    				case 9:table++;break;
    				case 10:enter++;break;
    Do not use magic numbers

    Use ' ', '\t' , '\n' - they are readable
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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