Store only numbers from user input

Question

Raldi 2011-12-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/22822-store-only-numbers-from-user-input

采纳的回答： Walter Roberson

Hi guys

Is there a way to store only the numbers from lets say an input of the type S^2+67*s+98

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Answer 1

Walter Roberson 2011-12-1

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https://ww2.mathworks.cn/matlabcentral/answers/22822-store-only-numbers-from-user-input#answer_30006

在 MATLAB Online 中打开

numstrs = regexp(TheString, '-?\d+', 'match');

then convert each of the cell strings returned in numstrs to numeric form. The -? part is to recognize an optional negative sign.

If you want to be able to accept floating point numbers, or if you want to recognize fractions as being numbers, or if you want to recognize pi as being a number, then the task gets more difficult.

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Raldi 2011-12-1

No i think this will do, thank you Walter.

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Answer 2

Jan 2011-12-1

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/22822-store-only-numbers-from-user-input#answer_30008

在 MATLAB Online 中打开

Another approach from the times of Matlab 5.3 without REGEXP:

S = 'S^2+67*s+98';
S((S < '0' | S > '9') & S ~= '.') = ' ';
N = sscanf(S, '%g');

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Raldi 2011-12-1

Seems that i have another problem now. What if i only need the numbers that are lets say just before the letter S. I tried to figure it out from the matlab's help but with no luck.