How to determine whether a string is a space in php (three methods)

In PHP, it is relatively simple to determine whether a string is a space. This article will introduce various methods to determine whether a string is a space.

Method 1: Use the "trim" function

The "trim" function can be used to remove spaces before and after a string. If the length of the processed string is 0, it means that the original string consists only of spaces, as shown below:

$str = " "; 
if(strlen(trim($str)) == 0){ 
echo "该字符串为仅由空格组成"; 
}else{ 
echo "该字符串不是仅由空格组成"; 
}

Method 2: Use the "ctype_space" function

The "ctype_space" function is used Determine whether a string contains whitespace characters, including spaces, tabs, newlines, etc. True will be returned only if the string consists entirely of these characters.

$str = " "; 
if(ctype_space($str)){ 
echo "该字符串为仅由空格组成"; 
}else{ 
echo "该字符串不是仅由空格组成"; 
}

Method 3: Use regular expressions

Regular expressions can be used to match all spaces in the string. If the string only contains spaces, you can use preg_match to determine whether the matching result is 1. As shown below:

$str = " "; 
if (preg_match('/^\s*$/', $str)) { 
echo "该字符串为仅由空格组成"; 
}else{ 
echo "该字符串不是仅由空格组成"; 
}

Although the above three methods can all determine whether a string is a space, it is simpler to use the "trim" function or "ctype_space" function to directly determine whether it is a space. Therefore, in actual use, we can choose a method that suits us according to our needs.

Finally, it should be noted that the above methods are all based on the judgment of spaces (' ') in ASCII codes. In Unicode encoding, there are other space characters, such as full-width spaces, zero-width spaces, etc., which need to be judged using corresponding methods.

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