Input redirection
Hello everybody.
I need help with input redirection. I'm using it to read in a file full of
integer values which I'm putting into array. After sorting it , I'm prompting
a user to enter a value to search for in the array but my program skips
the scanf command. My guess this happens because this input redirection
thingy turns on once I typed in '<' at the prompt and it remains on the whole time.
If it is in fact so, how do I turn it off?
I need help with input redirection. I'm using it to read in a file full of
integer values which I'm putting into array. After sorting it , I'm prompting
a user to enter a value to search for in the array but my program skips
the scanf command. My guess this happens because this input redirection
thingy turns on once I typed in '<' at the prompt and it remains on the whole time.
If it is in fact so, how do I turn it off?
Input redirection isn't an on or off thing. Your program has one standard input stream.
Instead of using input redirection, prompt the user for the file name and read the file yourself.
Instead of using input redirection, prompt the user for the file name and read the file yourself.
It's not getting skipped, your theory was correct - it is reading from the file.
Why do you have to use input redirection? There is no way to do what you want.
Why do you have to use input redirection? There is no way to do what you want.
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Dang!
My Proff wants me to read in a file using input redirection,
put the values in the array, copy it, sort one of the copies and than use
linear and binary searches on both copies of the array and print out the
position and number of comparisons it took to find a value in all four cases.
The value to search for should too be obtained from user using standard input.
My Proff wants me to read in a file using input redirection,
put the values in the array, copy it, sort one of the copies and than use
linear and binary searches on both copies of the array and print out the
position and number of comparisons it took to find a value in all four cases.
The value to search for should too be obtained from user using standard input.
Can't I 'close' the file somehow?
I will probably need to look argument vector for that, right?
I will probably need to look argument vector for that, right?
You should contact your professor - maybe there is a misunderstanding? It is not possible to change the standard input while the program is running. Once a program starts, whatever it is inputting from is what it will always be inputting from.
You can, however, pass the number to search for as an argument:
EDIT: If you close the file, that's closing the standard input stream. AKA, no more input, ever.
You can, however, pass the number to search for as an argument:
myprogram.exe 42 < input.txt |
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EDIT: If you close the file, that's closing the standard input stream. AKA, no more input, ever.
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I got the idea. Thank you.
Just not completely clear what is going on in this line
why const* twice?
Just not completely clear what is going on in this line
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char const *const *arguments in particular.why const* twice?
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The
The first
The second
You can change the pointer to the pointers to the characters. Adding a third
const keyword affects the thing to its left.The first
const means you cannot change the individual characters.The second
const means you cannot change the pointers to the characters.You can change the pointer to the pointers to the characters. Adding a third
const would mean you could not:char const *const *const arguments
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