how to compare string?
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i want to take input fuel=CH4 or CO or Co2, %its num + string input if fuel==CH4 % if fuel is CH4 i need to fix some value for variable %if fuel is Co or Co2 i need to fix some value can you please help me how to do it?
采纳的回答
Try this:
fuel=input('select the gaseous component CH4,ethane,propane,butane,H2,CO,CO2,N2\n');
if prod(ismember(fuel,'CH4'))
density=0.716; %kg/m^
LCV=35.83; %MJ/m^3
cc=1; hh=4; oo=0; nn=0;
TMmass=cc+hh+oo+hh;
disp('total mass of CH4');
disp(TMmass);
end
if prod(ismember(fuel,'ethane'))
density=1.342; %kg/m^3
disp(density);
LCV=63.76; %MJ/m^3
disp(LCV);
cc=2;
disp(cc);
hh=6;
disp(hh);
oo=0;
disp(oo);
nn=0;
disp(nn);
TMmass=cc+hh+oo+hh;
disp('total mass of CH4');
disp(TMmass);
end
Do not forget to enter your input in char form. Like
>>'CH4'
or
>>'ethane'
5 个评论
SRIGUHAN MURUGASUNDARAM
2018-1-18
prod(ismember(...)) ?
If you want to test that all values are members, then it would make sense to use all not prod.
all(ismember(...))
In addition, the test will say that CH4, C, H, CH4CH4C are all the same chemical. Why not use strcmp?
Birdman
2018-1-18
Thanks.
This is a buggy way to compare strings. It will work incorrectly even if the order of the characters is different, or if any characters are repeated. Avoid using this code.
Strings should be compared simply using strcmp and strcmpi. See the other answers for simpler and much more robust code.
Birdman
2018-1-18
Yes, thank you for attention.
更多回答（2 个）
Steven Lord
2018-1-18
The approach Birdman suggested won't work if the user enters more characters than you expected.
fuel = 'CH4CC4'
prod(ismember(fuel, 'CH4')) % returns 1
It also won't work if the user enters lower-case characters when you expected upper-case.
prod(ismember('ch4', 'CH4')) % returns 0
Use isequal, strcmp, strcmpi, or a switch / case statement. To handle case matching, you might also want to use upper or lower to convert the input into a consistent case.
isequal(fuel, 'CH4') % false
strcmp(fuel, 'CH4') % false
switch fuel
case 'CH4'
result = true
otherwise
result = false
end
3 个评论
SRIGUHAN MURUGASUNDARAM
2018-1-18
SRIGUHAN MURUGASUNDARAM
2018-2-27
Steven Lord
2018-2-28
Please use the Ask button at the top of the page to ask a new question. That way I can read it and so can others who may respond before I can.
Guillaume
2018-1-18
2 个投票
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