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 MATLAB's 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