i have a code like this:
I only entered '1' , then I hit enter, this value should be read in. I hit enter the second time, the scanf() should return a false and jump out of the function. But it did not work in that way, it only jumps out until I entered a letter. could anyone tell me the reason? thanks.Code:int store(double a[],int limit) { int i=0; while(i<limit&&scanf("%lf",&a[i])==1) i++; return i; }
scanf stop reading input when some part of the input read doesn't match its format string (AKA, when you press enter). It then returns the number of input items assigned, in your case, 1. That's why it doesn't break out of the loop.
Teacher: "You connect with Internet Explorer, but what is your browser? You know, Yahoo, Webcrawler...?" It's great to see the educational system moving in the right direction
but when I pressed the second time, scanf() should return '0' and it should break out. how can you explain this?Originally Posted by Happy_Reaper
no, you're still in the scanf function until an input item doesn't match the format string.
Teacher: "You connect with Internet Explorer, but what is your browser? You know, Yahoo, Webcrawler...?" It's great to see the educational system moving in the right direction
when you use some numeric format scanf ignores whitespaces, so your second \n symbol is just ignored as the first one. and scanf jsut continues to wait for the input.
but when you enter the letter - it is not whitespace and is not ignored.
But because this input is not consistent with the format - scanf exits and returnes 0
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
– David J. Wheeler
If you want the behaviour you described, use fgets() in conjunction with sscanf().
dwk
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