matlab struct initialization issue

I'm trying to initialize a strut which would have fields that represent age groups like <39, 40-49, 50-59 and so on. So I tried the following

x = struct('below39',{},'AG 40 to 49',{}); but it gives me an invalied field name error. I also tried

x = struct('below39',{}); and that worked. I'm not sure why is this an issue. Any insights would eb helpful.

Answer 1

[Ameer Hamza]

In MATLAB, the struct fieldnames cannot have spaces. The following will work

x = struct('below39',{},'AG_40_to_49',{})

Read here about rules to for creating a fieldname: https://www.mathworks.com/help/matlab/ref/struct.html#d122e1258552

[Anmol Pardeshi]

Thanks Ameer. Although one more thing worth noting is that the first character must be a alphabet and not number. In that light, '40_to_49' would not work. It should start with a alphabet.

[per isakson]

See matlab.lang.makeValidName and isvarname()

[Ameer Hamza]

@Anmol Pardeshi, yes. The link mentions the rules to define a fieldname.

@Per Isakson, Thanks for the information.