How can I make a string array consisting of strings with numerical suffixes?

I want to make a 50x1 array that consists of 'sub01', ‘sub02’, ‘sub03’, ‘sub04’, …, ‘sub50’.

And this is my code, but it doesn't work

Sub=[];
for i=1:50
    Sub(i,1) = str2num("sub%2d",i);
end

Error using str2num
Incorrect number of arguments. Each parameter name must be followed by a corresponding value.

Please help me ☹️

Answer 1

[Cris LaPierre]

str2num won't work with a word ("sub"). It's also unnecessary if you are using sprintf.

One other correction I would make is in how you preallocate your array. The empty brackets initializes your variable Sub as a double, so all strings will appear as NaN. You need to initiallize as an empty string.

Try something like this.

Sub = strings;
for i=1:50
    Sub(i,1) = sprintf("sub%02d",i);
end
% view result
Sub

Sub = 50×1 string array
    "sub01"
    "sub02"
    "sub03"
    "sub04"
    "sub05"
    "sub06"
    "sub07"
    "sub08"
    "sub09"
    "sub10"
    "sub11"
    "sub12"
    "sub13"
    "sub14"
    "sub15"
    "sub16"
    "sub17"
    "sub18"
    "sub19"
    "sub20"
    "sub21"
    "sub22"
    "sub23"
    "sub24"
    "sub25"
    "sub26"
    "sub27"
    "sub28"
    "sub29"
    "sub30"

[Cris LaPierre]

Not quite the same result, but if you don't care about the leading 0, here's another way to do this.

Sub = "sub" + (1:50)'

Sub = 50×1 string array
    "sub1"
    "sub2"
    "sub3"
    "sub4"
    "sub5"
    "sub6"
    "sub7"
    "sub8"
    "sub9"
    "sub10"
    "sub11"
    "sub12"
    "sub13"
    "sub14"
    "sub15"
    "sub16"
    "sub17"
    "sub18"
    "sub19"
    "sub20"
    "sub21"
    "sub22"
    "sub23"
    "sub24"
    "sub25"
    "sub26"
    "sub27"
    "sub28"
    "sub29"
    "sub30"

[재훈]

Thank you ;)

Answer 2

[Walter Roberson]

compose("sub%02d",1:50).'

[재훈]

Thank you ;)

[Stephen23]

+1 very neat