pointers to pointers within structs

This is a discussion on pointers to pointers within structs within the C Programming forums, part of the General Programming Boards category; HI Guys my latest program needs to access an array through a pointer within a struct by using a pointer ...

  1. #1
    Registered User
    Join Date
    Aug 2003
    Posts
    2

    Angry pointers to pointers within structs

    HI Guys

    my latest program needs to access an array through a pointer within a struct by using a pointer to that struct itself. im at a loss as to how to do this. i can access non-pointer elements in the same struct (i.e bPtr->digits), i just am unsure how to access the array under my main function from within my ReadBinary function using only pointers. in the ReadBinary function also, after the scanf function has finished the while function is skipped, i beleive becuase the scanf function ends with the newline character. any ideas on how to fix this would also be most welcome. Cheers

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    struct BinaryRec
    {
    	char* aPtr ;
    	int digits ;
    };
    typedef struct BinaryRec Binary ;
    
    void readBinary(/*Binary* bptr*/) ;
    //void printBinary(const Binary* bptr) ;
    
    int main()
    {
    Binary num ;
    char array[] ;
    
    Binary* bPtr = (Binary*)malloc(sizeof(Binary)) ;
    //num.aPtr = (char*)malloc(num.digits*sizeof(char)) ;
    
    readBinary(bPtr) ;
    
    return 0;
    }
    
    void readBinary(Binary* bPtr)
    {
    char x ;
    
    int i, n ;
    
    printf("Please Enter Number of Binary Digits:") ;
    scanf("%d", &n) ;
    
    bPtr->digits = n ;
    
    printf("--%d--\n", bPtr->digits) ;
    
    printf("Please Enter Binary Number:") ;
    
    while((x = getc(stdin)) != '\n')
    	{
    		if(x != 48 && x != 49)
    			{
    			printf("\nInvalid Input\n") ;
    			exit(1) ;
    			}
    		else
    			{
    			/*I Need to access the array at this point by using the pointers aPtr and bPtr to input the characters from getc 	
                           	printf("%c", x) ;
    			i++ ;
    			}
    	}
    
    return ;
    
    }

  2. #2
    ATH0 quzah's Avatar
    Join Date
    Oct 2001
    Posts
    14,826
    Code:
    struct boo bar
    {
        char *array;
    };
    struct foo *pbar;
    
    pbar = &bar;
    pbar->array = malloc( SOME_SPACE );
    ptab->array[x] = '\0';
    Is that what you're looking for?

    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
    Registered User
    Join Date
    Aug 2003
    Posts
    2
    Thanks, that was very helpful. i was going about it all wrong so i've managed to solve the pointer problem, although i still have the scanf problem where it skips any character input functions, even using scanf and %c itself. Any other thoughts anyone?

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