I’m writing a function that perform some authentications actions. I have a file with all the user_id:password:flag couples structured like this: Users.txt user_123:a1b2:0 user_124:a2b1:1 user_125:a2b2:2 This is the code: How can I manage the EOF reaching? I saw that when EOF is reached fgets doesn’t edits anymore the usr_psw_line but neither returns a NULL pointer. … Read more
The function fgets read until a newline (and also stores it). fscanf with the %s specifier reads until any blank space and doesn’t store it… As a side note, you’re not specifying the size of the buffer in scanf and it’s unsafe. Try:
The elegant way: The slightly ugly way: The slightly strange way: Note that the strtok function doesn’t work as expected if the user enters an empty string (i.e. presses only Enter). It leaves the \n character intact. There are others as well, of course.
here a concatenation solution:
There are multiple differences. Two crucial ones are: fgets() can read from any open file, but scanf() only reads standard input. fgets() reads ‘a line of text’ from a file; scanf() can be used for that but also handles conversions from string to built in numeric types. Many people will use fgets() to read a line of data and then use sscanf() to dissect it.
My guess is that the file is failing to open, and you’re still passing it to fgets. Your if(rd==NULL) doesn’t stop execution of the fgets if it’s null, it just prints out a message and continues with execution. Some very basic errorr handling:
In order to use gets safely, you have to know exactly how many characters you will be reading, so that you can make your buffer large enough. You will only know that if you know exactly what data you will be reading. Instead of using gets, you want to use fgets, which has the signature (fgets, if it reads … Read more