Re:Everything I wish I knew when learning C
by 0xbadcafebee on Monday November 28, 2022 @07:53PM
(#33782208)
The reason you would want to use memcpy would be if 1) you already know what the length is, 2) if you need a custom validator for your input, 3) you don't want to validate your input (however snprintf() is doing that), 4) if the string may include nulls or there is no null terminator.
But the fifth reason may be that depending on snprintf as your "custom-validator-and-encoder-plus-null-terminator" may introduce subtle bugs in your program if you don't know exactly what snprintf is doing under the hood and what its limitations are. By using memcpy and a custom validator, you can be more explicit about how data is handled in your program and avoid uncertainty.
(by "validate" I mean handle the data as your program expects. this could be differentiating between ASCII/UTF-8/UTF-16/UTF-32, adding/preserving/removing a byte-order mark, eliminating non-printable characters, length requirements, custom terminators, or some other requirement of whatever is going to be using the new copy of the data)
But the fifth reason may be that depending on snprintf as your "custom-validator-and-encoder-plus-null-terminator" may introduce subtle bugs in your program if you don't know exactly what snprintf is doing under the hood and what its limitations are. By using memcpy and a custom validator, you can be more explicit about how data is handled in your program and avoid uncertainty.
(by "validate" I mean handle the data as your program expects. this could be differentiating between ASCII/UTF-8/UTF-16/UTF-32, adding/preserving/removing a byte-order mark, eliminating non-printable characters, length requirements, custom terminators, or some other requirement of whatever is going to be using the new copy of the data)