Thread: Using scanf in a for loop

  1. #1
    Registered User
    Join Date
    Dec 2007

    Using scanf in a for loop

    how do you make scanf read in numbers in a for loop?? this is what i want it to do:
    example input:
    45 34 67 78
    scanf terminates after space is pressed so how do i get around that problem?

    this is my code so far:
    #include <stdio.h>
    void swap(int *p, int *q)
        int tmp;
        tmp = *p;
        *p = *q;
        *q = tmp;
    void bubble (int a[10])
    	int i, j;
    	for (i = 0; i < 9; i++)
    		for (j = 9; i < j; j--)
    		if (a[j - 1] > a[j])
    			swap(&a[j - 1], &a[j]);
    int	main (void)
    	int i;
    	int a[10];
    	for (i = 0; i < 10; i++){
    		scanf ("%d\n", &a[i]);}
    	bubble (a);
    	for (i = 0; i < 8; i++)
    	printf(" %d", a[i]);
    	return 0;
    what should i put into the scan set for scanf to make it work? thanks

  2. #2
    Kernel hacker
    Join Date
    Jul 2007
    Farncombe, Surrey, England
    Maybe because you are asking it to read until a newline with "%d\n", so you need to enter multiple lines, not spaces?

    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  3. #3
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    Just drop the \n from the scanf call.

    \n doesn't just match a single \n, it matches any sequence of any length of any white-space character.
    So the input of the 10th number will only return AFTER you type a non-whitespace character after your 10th number.
    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.

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