countdown the received character
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Hi guys, I have a function which will accept the characters and n, this function is a cell array with strings of decreasing lengths, from the integer n to 1. For example, when I type buildstr('a',4), the answer should be 'abcd' 'abc' 'ab' 'a'. However the code below doesnt satisfy my requirement. Can someone point out the error code?
function str=buildstr(ch,n)
temp='';
if(n<0)
str='';
else
str=cell(n,1);
for i=n:1
if(i==1)
str(i)={char(ch)};
else
temp=char(str(i+1));
str(i)={strcat(temp,char(ch))};
end
end
end
采纳的回答
Star Strider
2014-11-17
You’re almost there.
if(n<0)
str='';
else
str=cell(n,1);
for i=n:-1:1
if(i==n)
str{i}=char(ch);
else
temp=char(str{i+1}+1);
str{i}=strcat(char(ch),temp);
end
end
end
There were three problems:
- Your loop wasn’t iterating because in MATLAB, for loops by default count upward, so if the terminal value is less than the initial value, the loop is satisfied and never iterates. You need to decrement it by telling it to count down, specifying the interval to (in this instance) to be -1;
- Your ‘temp’ variable subscript needs to ‘look back’ (which is to say to add 1 to ‘i’) at every iteration, and add 1 to the previous value of ‘str’;
- Your strcat arguments were reversed.
A minor observation: it’s best to not use ‘i’ or ‘j’ as loop counters. They are the imaginary operators in MATLAB.
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