I'm learning about file operations in C++, and I've come across the seekp and seekg functions. My textbook mentions adding an 'L' after the number of bytes to treat it as a long, but it doesn't really explain why it needs to be a long. For example, when I use file.seekp(100L, ios::beg), I understand it moves the write position 100 bytes from the beginning of the file, but I'm confused about the significance of the 'L'. Isn't a long at least 4 bytes? Wouldn't that make it 400 bytes? I'm not sure I'm getting it right, and I've searched for similar questions without finding anything helpful. Any insights would be appreciated!
3 Answers
The 'L' indicates the number is a long format. This is to help the compiler know what kind of number you're working with. While the compiler usually does the right thing and converts automatically, using 'L' ensures you're explicitly telling it what you're working with, preventing potential issues—especially with larger numbers.
You don’t strictly need the 'L' for it to work, but it's there to avoid compiler warnings. Without it, if the compiler thinks you're converting an `int` to a `long`, it might throw a fit. In real situations, instead of hardcoding values like 100, you'd typically use a long variable, so this 'L' just keeps things tidy and warning-free.
In C++, the 'L' means it's a "long int". It shouldn't really be necessary since most compilers will change it to a long if the function expects that, but adding it is good form to avoid warnings, especially if you have strict warning settings. It saves you headaches during compiling!
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