string replacement in files

14/10/2018

I'm slowly rewriting my website generator in C and for it I required an easy way to write an input file to an output file replacing every instance of something with another string. So I made this convenience function that might be useful elsewhere one day.

int replaceinfile(char *originalfile, char *destinationfile, char *placeholder,
								char *replacement);
// 0 = failure, 1 = success

replaceinfile("input.txt", "output.txt", "%PLACEHOLDER%", "replacement string");

Normal text file

%PLACEHOLDER%
%PLACEHOLDER%
%PLACEHOLDER%

With lines and whatever, %PLACEHOLDER%

123%PLACEHOLDER%123	
ok %PLACEHOLDER% ok

Normal text file

replacement string
replacement string
replacement string

With lines and whatever, replacement string

123replacement string123	
ok replacement string ok