Programming and Data Types

Comparing Strings For Equality

There are four functions that determine if two input strings are identical:

• strcmp determines if two strings are identical.
• strncmp determines if the first n characters of two strings are identical.
• strcmpi and strncmpi are the same as strcmp and strncmp, except that they ignore case.

Consider the two strings

• str1 = 'hello';
  str2 = 'help';
  

Strings str1 and str2 are not identical, so invoking strcmp returns 0 (false). For example,

• C = strcmp(str1,str2)  
  C =
      0
  

Note    For C programmers, this is an important difference between the MATLAB strcmp and C's strcmp(), which returns 0 if the two strings are the same.

The first three characters of str1 and str2 are identical, so invoking strncmp with any value up to 3 returns 1.

• C = strncmp(str1,str2,2)
  C =
      1
  

These functions work cell-by-cell on a cell array of strings. Consider the two cell arrays of strings

• A = {'pizza';'chips';'candy'};
  B = {'pizza';'chocolate';'pretzels'};
  

Now apply the string comparison functions.

• strcmp(A,B)
  ans =
      1
      0
      0
  
  strncmp(A,B,1)
  ans =
      1
      1
      0
  

String Comparisons

Comparing for Equality Using Operators