"Does anyone have an idea ?"
Yes: Do NOT do this! Magically accessing variable names is one way that beginners force themselves into writing slow, complex, buggy code that is hard to debug. Read this to know why:
The simplest solution is to not get into this situation in the first place. Most likely you did not sit there are type all of those names out by hand, so the correct place to fix your code is where those variables were first created in the workspace. For example, if they were load-ed from a .mat file, then simply load them into output variables (which are structures):
S = load(...)
If you tell us how those variables got into your workspace, then we can show you how to write simpler, neater, more robust code to process them all.
