quick pointer question

This is a discussion on quick pointer question within the C Programming forums, part of the General Programming Boards category; ok so I'm refreshing myself on pointers real quick, I thought I could directly pass the address of a variable ...

  1. #1
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    Jul 2007
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    quick pointer question

    ok so I'm refreshing myself on pointers real quick, I thought I could directly pass the address of a variable to a function and not have to pass it a pointer, am I wrong? But the only way I've gotten this file to work is passing a ptr instead of the address of units. So can it be done without the additional pointer declared in main? (and yes I'm trying to do it without an external variable)

    Code:
    #include <stdio.h>
    // int units = 0;
    void critic(int *g);
    int main(void)
    {
    	int units = 0;
    	int *ptr;
    	ptr = &units;
    
    	printf("How many pounds to a firkin of butter?\n");
    	scanf("&#37;d", &units);
    	while(units != 56)
    		critic(&ptr);
    	printf("You must have looked it up!\n");
    	
    	return 0;
    }
    
    void critic(int *g)
    	{
    	printf("No luck, chummy. Try again.\n");
    	scanf("%d", *g);
    	}

  2. #2
    Sweet
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    pass &units instead of ptr, get rid of ptr. Then in critic make that g instead of *g in scanf

  3. #3
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    doh! right because it's a pointer it's already an address, thanks

  4. #4
    Deathray Engineer MacGyver's Avatar
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    Mar 2007
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    3,211
    Correct. I think some people are sometimes thrown off by the fact that a pointer is really an address. Therefore when a function requires a pointer, you don't need to actually declare a pointer variable in the calling function necessarily. Sometimes the address of a "normal" variable will do just fine. It's a case of needing to RTM, or equiv. documentation for the function and what it expects.

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