Week 9, Assignment 2

1 次查看（过去 30 天）

Ajith Thomas 2019-8-19

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476673-week-9-assignment-2

回答： Raheem Ullah 2022-8-17

Write a function called char_counter that counts the number of a certain character in a text file. The function takes two input arguments, fname, a char vector of the filename and character, the char it counts in the file. The function returns charnum, the number of characters found. If the file is not found or character is not a valid char, the function return -1. As an example, consider the following run. The file "simple.txt" contains a single line: "This file should have exactly three a-s...

function charnum=char_counter(fname,a)
fid=fopen(fname,'rt');
if fid<0
    charnum=-1;
    fprintf('error\n');
    return;
end
if ischar('a')==0
    return;
end
if fid>0 && ischar(a)
    line=fgets(fid);
    n=0;
    for n=n+count(line,a)
    end
    charnum=n;
else charnum=-1;
end
if ischar(a)==0
    charnum =-1;
elseif charnum==0
    charnum=0;
    return;
end
fclose(fid);

why second error is coming?

6 个评论
显示 4更早的评论隐藏 4更早的评论

Guillaume 2019-8-19

The code is much better. However,

if the file is valid (fid >= 0) but a is not, you quit the function without closing the file
double(a) == 32 is exactly the same as a == ' '. The latter is a lot clearer as to the intent.
Your for loop doesn't make any sense. By chance, your function will produce the correct result if the input has one line only.
Again, testing if something is 0 and then setting it to 0 if it is, doesn't make sense.

my question is which all characters should be eliminated

Why should any of them be eliminated?

Steven Lord 2019-8-19

Why is the space character not a valid character? Nothing in the text of the assignment that you've posted says it's invalid.

By the way, I agree with Guillaume that a == ' ' is a clearer statement of intent. Calling the isspace function is even clearer, though it may be a little more permissive about what's a space than you want (are tab, line feed, or newline spaces? They are to isspace.)

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Raheem Ullah 2022-8-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476673-week-9-assignment-2#answer_1027895

在 MATLAB Online 中打开

function charnum=char_counter(fname,character)
fid=fopen(fname,'rt')
n=0
p=ischar(character)
if(fid<0 || p==0)
 
    charnum=-1
    return
else   
oneline=fgets(fid)
while  ischar(oneline)
        for ii=1:length(oneline)
            if(oneline(ii)==character)
            n=n+1
            end
        end
 oneline=fgets(fid)
end
end
charnum=n;
fclose(fid);
end