This question already has answers here:
Difference between scanf and scanf_s
(3 answers)
Closed 8 years ago.
Although my program gives the required output. There are many warnings showing scanf() shouldn't be used and try using scanf_s() instead.
Possible cause of this warning??
This is happening to all the programs which are using the scanf function. Even simple addition of numbers.
With scanf, with some format arguments it is possible to crash your program if you use unlimited size inputs. scanf_s requires to provide size of output buffers, thus limiting possibility of buffer overflows (provided you specify output buffer sizes correctly).
Related
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fgets doesn't work after scanf [duplicate]
(7 answers)
Closed 2 years ago.
discrepency
Hi everyone,
Currently working on some Harvard's CS50 problems, I've noticed that substituting get_int by scanf makes my program behave erratically.
The problem at hand here consists in creating a plurality election mockup. And the simple fact that I replace get_int by scanf in order to register the number of votes during the election ends up signalling the first vote as 'invalid' (a function later in the code is charged of checking vote validity).
I've checked multiple times, used the debugger, but to no avail.
Any hints as to why that happens would be deeply appreciated.
scanf("%i", &vote_count) does not consume anything after the number. What comes after the number is most likely a newline character, which is what will be seen by get_string. That probably causes the first name to be an empty string.
You should see all that if you use a debugger.
This question already has answers here:
How do you allow spaces to be entered using scanf?
(11 answers)
Closed 3 years ago.
I need to read the text using scanf, but what I know scanf is reading characters to the first space. I don't know that it's possible to read more words into the array by scanf and i have no any idea.
That's not correct; scanf reads according to the format string you give it.
Nothing keeps you from using a format that reads past spaces, returns, or whatever else, for example scanf("%50c",buffer); will read 50 characters, no matter what they are; or scanf("%[^|]", buffer); will read everything up the first |. Read up on the definition of the scanf family.
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Limit on the number of arguments to main in C
(4 answers)
Closed 8 years ago.
I am writing an a general c program which accepts command line arguments and my doubt is no of command line arguments we can pass and why, on what factor does it depends.
The standard doesn't say nothing about the limit of arguments, so INT_MAX (typically 2^31 - 1) is assumed.
On Linux, you get the maximum character length of arguments in a shell by running:
getconf ARG_MAX
More info
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Using fflush(stdin)
(7 answers)
Closed 8 years ago.
Okay , i was solving a problem in code chef (very easy).
It briefly states that :
-A question as a string will be given , and another string has to be produced which does not have any letter used in question string. Uppercase and lowercase are assumed to be same.
-If all alphabets have been used just print ~ sign.
My whole logic is correct except i caught error in my input and this was caused by using fflush(stdin) before gets(). Please explain why was this an error ? Ignore the rest of the code.
Link to problem :http://www.codechef.com/problems/NOLOGIC/
Link to wrong solution :http://www.codechef.com/viewsolution/3881817
Link to corrected solution :http://www.codechef.com/viewsolution/3881827
Pls Note :In corrected code i have only made change in not using fflush(stdin) and using getchar()
Being that the behavior of fflush(stdin) is implementation specific; and being that the implementation (for this question) is unknown, the behavior will also be unknown.
You may safely expect the behavior of fflush(stdin) to be unpredictable.
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Turbo C++: Why does printf print expected values, when no variables are passed to it?
(5 answers)
Closed 9 years ago.
int a=9,b=6,c=3;
printf("%d%d%d");
I executed this in code blocks 10.05. I got some garbage values. But in a website the output was given as 3 6 9. What is the correct one?
You will get garbage values, because you're not providing any arguments to the printf() call.
The correct code would be
printf("%d%d%d",c,b,a);
(to get the numbers in the order quoted)
The correct one is neither of the two you described. Since no values were passed to printf, only the formatters, whatever was on the stack at that moment (which is undefined) is passed.
What is the correct output of this statement?
This code invokes undefined behaviour and so there is no correct output. The output is undefined.
The code invokes undefined behaviour because the format string you passed to printf requires you to pass more parameters (3) than you supplied (0).