字符串比较函数---2
字符串比较函数---2
4. 把算法转化为相应的MATLAB语句function result = c_strcmp(str1,str2)%C_STRCMP Compare strings like C function "strcmp"% Function C_STRCMP compares two strings, and returns% a -1 of str1 < str2, a 0 if str1 == str2, and a% +1 if str1 > str2.% Define variables:% diff -- Logical array of string differences% msg -- Error message% result -- Result of function% str1 -- First string to compare% str2 -- Second string to compare% strings -- Padded array of strings% Record of revisions:% Date Programmer Description of change% ==== ========== =====================% 10/18/98 S. J. Chapman Original code% Check for a legal number of input arguments.msg = nargchk(2,2,nargin);error(msg);% Check to see if the arguments are stringsif ~(isstr(str1) & isstr(str2)) error('Both str1 and str2 must both be strings!')else % Pad strings strings = strvcat(str1,str2); % Compare strings diff = strings(1,:) ~= strings(2,:); if sum(diff) == 0 % Strings match, so return a zero! result = 0; else % Find first difference between strings ival = find(diff); if strings(1,ival(1)) > strings(2,ival(1)) result = 1; else result = -1; end endend
5. 检测程序我们必须用多个字符串对程序进行检测>> result = c_strcmp('String 1','String 1')result = 0>> result = c_strcmp('String 1','String 1 ')result = 0>> result = c_strcmp('String 1','String 2')result = -1>> result = c_strcmp('String 1','String 0')result = 1>> result = c_strcmp('String 1','str')result = -1 第一次检测返回0，是因为两字符串是相同的。第二次也返回0，因为两字符串也是相等的，只是末端空格不同，末端空格被忽略。
第三次检测返回-1，因为两字符串第一次的不同出现在第8位上，且在这个位置上“1”<“2”。第四次检测将返回1，因为两字符串第一次的不同出现在第8位上，且在这个位置上，“1”>“0”。第五次检测将会返回-1，因为两字符串的第一个字符就不同，在ascii的序列上“S”<“s”。这个函数工作正常。
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