c# - Concat list null check -

i have 5 variables in have individual data, after concatenating respective charge volumes 1 variable. works fine.

now issue suppose have 1 data (var ccpcv has data) , rest not have data, var combinedpcv line breaks because charge volume null other variables. there can n number of scenarios (2 have data, 3 have data etc).

one approach check each individual variable null value , null check on combination of variables.

please suggest better approach.

var ccpcv = (guidedpcvyear1ccviewmodel)wizard.steps[est bettgwizard.orderedsteps[typeof(guidedpcvyear1ccviewmodel)]]; var cpcpcv = (guidedpcvyear1cpcviewmodel)wizard.steps[wizard.orderedsteps[typeof(guidedpcvyear1cpcviewmodel)]]; var vpaypcv = (guidedpcvyear1vpaviewmodel)wizard.steps[wizard.orderedsteps[typeof(guidedpcvyear1vpaviewmodel)]]; var bippcv = (guidedpcvyear1bipviewmodel)wizard.steps[wizard.orderedsteps[typeof(guidedpcvyear1bipviewmodel)]]; var gnicsccpcv = (guidedpcvyear1ccgnicsviewmodel)wizard.steps[wizard.orderedsteps[typeof(guidedpcvyear1ccgnicsviewmodel)]];  var combinedcv = ccpcv.chargevolumes.convertall(cv=>cv).concat(cpcpcv.chargevolumes.convertall(x=>x).concat(vpaypcv.chargevolumes.convertall(z=>z).concat(bippcv.chargevolumes.convertall(a=>a).concat(gnicsccpcv.chargevolumes.convertall(s=>s))))); year1chargevolumes = combinedcv.tolist(); 

you write helper method so:

public static ienumerable<t> concattreatingnullsasempty<t>(params ienumerable<t>[] sequences) {     return          sequence in sequences sequence != null         item in sequence         select item; } 

then use follows:

ienumerable<int> seq1 = enumerable.range(1, 5); ienumerable<int> seq2 = null; ienumerable<int> seq3 = enumerable.range(6, 5); ienumerable<int> seq4 = null; ienumerable<int> seq5 = enumerable.range(11, 5);  var numbers = concattreatingnullsasempty(seq1, seq2, seq3, seq4, seq5);  console.writeline(string.join(", ", numbers)); // prints 1, 2, ..., 14, 15 

i think code this:

var combinedcv = concattreatingnullsasempty(     ccpcv      .chargevolumes,      cpcpcv     .chargevolumes,     vpaypcv    .chargevolumes,     bippcv     .chargevolumes,     gnicsccpcv .chargevolumes);