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calling a variable in a string

Topic last updated 19 Jul 2010, by Simon Ford. 1 reply
James Ehrman
19 Jul 2010

Hi,

I have a program which opens a file and records some data. I would like it to be able to open several files, and thus call each file a different name so as not to over-write them. I thought of setting up a count which incremented after each file was closed, and in the command to open the next file there would be a variable which would provide the number of the file opened. However, I cannot figure out how to call this variable inside the string which names the file.

FILE *fp = fopen("/local/analog.txt","w");
is what I have so far, and I was thinking of something on the lines of:

FILE *fp = fopen("/local/analog_x.txt","w");
where "x" is the name of the count at the time the file was opened.

 

Thanks for your time,

 

Simon Ford
19 Jul 2010

Hi James,

You basically want to create a filename based on a variable, so you can use something like sprintf to create a string, then use that as your filename. So something like:

char filename[64];    
sprintf(filename, "/local/analog_%d.txt", x);
FILE *fp = fopen(filename, "w");
Hope that helps you!

Simon