how to get out of an if loop?

This is a discussion on how to get out of an if loop? within the C Programming forums, part of the General Programming Boards category; good day. what i want to do with my code is to perform dothisthing if the user's input string is ...

  1. #1
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    how to get out of an if loop?

    good day. what i want to do with my code is to perform dothisthing if the user's input string is equal to "doaction". i am looking for a way to exit condition 2 and return to condition 1 (waiting for user to input a new string) once the user presses the letter 's'. all of your input and ideas will much appreciated

    Code:
    int howlong;
    if (!(strcmp (USERINPUT,doaction)){               //condition 1
       if (howlong < 10 seconds){                        //condition 2
               dothisthing;
       }
    }

  2. #2
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    Quote Originally Posted by iwanttolearnc View Post
    good day. what i want to do with my code is to perform dothisthing if the user's input string is equal to "doaction". i am looking for a way to exit condition 2 and return to condition 1 (waiting for user to input a new string) once the user presses the letter 's'. all of your input and ideas will much appreciated

    Code:
    int howlong;
    if (!(strcmp (USERINPUT,doaction)){               //condition 1
       if (howlong < 10 seconds){                        //condition 2
               dothisthing;
       }
    }
    Short answer... You're not going to do that in 2 nested if statements.

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    thank you for the quick reply sir. do you have any suggestions on how i can go about doing that?

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    Quote Originally Posted by iwanttolearnc View Post
    thank you for the quick reply sir. do you have any suggestions on how i can go about doing that?
    You need to write your code for USERINPUT, doaction, dothisthing and howlong first. Once you have them before you, poducing good results, I'm pretty sure the rest is going to be obvious.

    Generally you break out of a block of code with, well, break; but that may not be appropriate in every case.

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    below is my code sir. its for a zilog microcontroller. is break appropriate for this case?
    Code:
            char userinput[4];
    	char led[] = {'l', 'e', 'd', '\0'};
    	
    	int howlong;
    
    	PDHDE = 0X03;	//zilog related
    	PDAF = 0X00;		//zilog related
    	PDDD = 0X00;		//zilog related
    
    
    	init_uart(_UART1 , _DEFFREQ , _DEFBAUD); //zilog related
    	select_port (_UART1); //zilog related
    
    	printf ("type led\n");
    	
    	userinput[0] = getch();
    	userinput[1] = getch();
    	userinput[2] = getch();	
    	userinput[3] = '\0';
    
    	if (!(strcmp(userinput, led))){		//condition 1
    		if(howlong++ < 0xFF){		//condition 2
    				PDOUT = 0X01;
    				delay();
    				PDOUT = 0x00;
    				delay();			
    		}
    
    	}

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    ive tried the break statement but it only does the action with pdout once. any ideas as to why?

    Code:
    char userinput[4];
    char led[] = {'l', 'e', 'd', '\0'};
    
    int howlong;
    
    PDHDE = 0X03;	//zilog related
    PDAF = 0X00;	 //zilog related
    PDDD = 0X00;	 //zilog related
    
    
    init_uart(_UART1 , _DEFFREQ , _DEFBAUD); //zilog related
    select_port (_UART1); //zilog related
    
    printf ("type led\n");
    
    userinput[0] = getch();
    userinput[1] = getch();
    userinput[2] = getch();	
    userinput[3] = '\0';
    
    if (!(strcmp(userinput, led))){	 //condition 1
    if(howlong++ < 0xFF){	 //condition 2
    PDOUT = 0X01;
    delay();
    PDOUT = 0x00;
    delay();	
    
    if (getch() == 's'){
    break;
    }
    }
    
    }
    Last edited by Salem; 09-14-2010 at 02:57 PM. Reason: code tags, but still no indentation

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    ive tried the break statement but it only does the action with pdout once. any ideas as to why?

    Code:
    char userinput[4];
    char led[] = {'l', 'e', 'd', '\0'};
    
    int howlong;
    
    PDHDE = 0X03;	//zilog related
    PDAF = 0X00;	 //zilog related
    PDDD = 0X00;	 //zilog related
    
    
    init_uart(_UART1 , _DEFFREQ , _DEFBAUD); //zilog related
    select_port (_UART1); //zilog related
    
    printf ("type led\n");
    
    userinput[0] = getch();
    userinput[1] = getch();
    userinput[2] = getch();	
    userinput[3] = '\0';
    
    if (!(strcmp(userinput, led))){	 //condition 1
    if(howlong++ < 0xFF){	 //condition 2
    PDOUT = 0X01;
    delay();
    PDOUT = 0x00;
    delay();	
    
    if (getch() == 's'){
    break;
    }
    }
    
    }
    Last edited by Salem; 09-14-2010 at 02:57 PM. Reason: It's CODE not QUOTE!

  8. #8
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    Just like the error says, you don't break out of an if statement. break is only for exiting loops, and an if statement is not a loop!

  9. #9
    and the hat of wrongness Salem's Avatar
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    Put the code in a loop which executes once.
    Code:
    do {
      if ( something ) break;
    } while ( 0 );
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  10. #10
    C++まいる!Cをこわせ! Elysia's Avatar
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    Learn to indent. Furthermore, if you need to stop processing if get a certain input, then why not process if you DON'T get the input? Thus you don't need break, only an if statement.


    Code:
    if (!(strcmp(userinput, led)))
    {     //condition 1
        if(howlong++ < 0xFF)
        {     //condition 2
            PDOUT = 0X01;
            delay();
            PDOUT = 0x00;
            delay();    
    
            if (getch() != 's')
            {
                // Continue processing
            }
    }
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.
    For information on how to enable C++11 on your compiler, look here.
    よく聞くがいい!私は天才だからね! ^_^

  11. #11
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    As has been pointed out "if" is not a loop, it's a one time conditional test.

    Try something like this...

    Code:
    howlong = 0;
    
    if (!(strcmp(userinput, led)))	 //condition 1
      while (howlong++ < 0xFF)	 //condition 2
        { PDOUT = 0X01;
          delay();
          PDOUT = 0x00;
          delay();	
          if (getch() == 's')
            break; }
    There are some excellent C language tutorials available for free download and/or study on the net. Google is your friend...


    [/code]

  12. #12
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    thanks!

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