Merging two wav files different lengths

How can I make the length number of two wav files the same, so the wav files can be merged?

[y1,fs1] = audioread('happy.wav');
[y2,fs2] = audioread('sad.wav');

S1=length(y1);
S2=length(y2);

Answer 1

[Adam]

doc interp1

if you need them the same length, but still covering the same time span. If you gave Signal Processing Toolbox then

doc resample

probably works fine too.