Working with strings [using scanf()]

This is a discussion on Working with strings [using scanf()] within the C Programming forums, part of the General Programming Boards category; I have sadly never been given a proper lesson in regards to strings when it comes to the C language, ...

  1. #1
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    Working with strings [using scanf()]

    I have sadly never been given a proper lesson in regards to strings when it comes to the C language, so I decided to hunt some threads myself, with little success. I am hoping I can be set to walk the right path with this thread

    My Task:
    Take a string as a user input using scanf. Compare braces and output "Missing Braces!!" if the open and close braces don't match in numbers.

    I'd appreciate it if it could be kept on basic functions and simple terms, I just need to read a string, probably loop through it and take note of open and close braces. I'm simply having trouble working with strings. Following is the code I've built so far:

    Code:
    #include <stdio.h>
    #include <string.h>
    
    int userInput[20];
    const int bOpen = 123;  // {
    const int bClose = 125; // }
    
    void takeInput(void) {
    	printf ("Please enter your string:\n");
    	scanf ("%s",userInput);
    }
    
    int checkBraces(void) {
    	int i, count=0;
    	for (i=0;i<20;i++) {
    		if (userInput[i] == bOpen) count ++;
    		else if (userInput[i] == bClose) count--;
    	}
    	return count;
    }
    
    void main (void) {
    	takeInput();
    	if (checkBraces() != 0)
    		printf ("\n\tMissing Braces!!\n");
    }

  2. #2
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    userInput should be a char array based on your wanting to use it for an argument in scanf as a %s. (did you not get a compile warning about this?)

    Overall, why use ints at all, since the native type for what you are entering is a char.?

    How about:
    Code:
    #include <stdio.h>
    #include <string.h>
    
    char  userInput[20];
    const char bOpen = '{';
    const char bClose = '{';
    
    void takeInput(void) {
    	printf ("Please enter your string:\n");
    	scanf ("%s",userInput);
    }
    
    int checkBraces(void) {
    	int i, count=0;
    	for (i=0;i<20;i++) {
    		if (userInput[i] == bOpen) count ++;
    		else if (userInput[i] == bClose) count--;
    	}
    	return count;
    }
    
    int main (void) {
    	takeInput();
    	if (checkBraces() != 0)
    		printf ("\n\tMissing Braces!!\n");
    
    	return 0;
    }

  3. #3
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    Thank you for the reply, in regards to avoiding chars, is due to a phobia with comparison operators, I always seem to do it wrong :P One final problem is the fact that my program cuts off at whitespaces, I need it to take a full string in until I hit enter.

    edit: doing a basic change it turned out to work without any issues:

    Code:
    scanf ("%[^\n]",userInput);
    Last edited by Luponius; 04-26-2011 at 09:47 AM.

  4. #4
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    This construct

    Code:
    %[^\n]
    is why I come to these boards. Just learned it the other day.

  5. #5
    CSharpener vart's Avatar
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    Quote Originally Posted by Luponius View Post
    edit: doing a basic change it turned out to work without any issues:
    you still have an issue of memory overrun in case when user enters string longer than 19 chars - add width modifier to your format to prevent it.
    Code:
    scanf ("%19[^\n]",userInput);
    also - would be a good idea - start using local vars instead of global ones. and pass them as parameters to your functions
    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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