在这里让我们一起学习，一起提高！
今天整理商贸程序，其中得需要计算一个字符串中某个字符出现的次数，就上网搜，好不容易找到一个函数substr_count（），
<?php
$text = 'This is a test' ;
echo strlen ( $text ); // 14
echo substr_count ( $text , 'is' ); // 2
// the string is reduced to 's is a test', so it prints 1
echo substr_count ( $text , 'is' , 3 );
// the text is reduced to 's i', so it prints 0
echo substr_count ( $text , 'is' , 3 , 3 );
// generates a warning because 5+10 > 14
echo substr_count ( $text , 'is' , 5 , 10 );
// prints only 1, because it doesn't count overlapped subtrings
$text2 = 'gcdgcdgcd' ;
echo substr_count ( $text2 , 'gcdgcd' );
?>
<?php
$text = 'This is a test' ;
echo strlen ( $text ); // 14
echo substr_count ( $text , 'is' ); // 2
// the string is reduced to 's is a test', so it prints 1
echo substr_count ( $text , 'is' , 3 );
// the text is reduced to 's i', so it prints 0
echo substr_count ( $text , 'is' , 3 , 3 );
// generates a warning because 5+10 > 14
echo substr_count ( $text , 'is' , 5 , 10 );
// prints only 1, because it doesn't count overlapped subtrings
$text2 = 'gcdgcdgcd' ;
echo substr_count ( $text2 , 'gcdgcd' );
?>
