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<html><!-- #BeginTemplate "/Templates/tmpl.dwt" --><!-- DW6 --><head><!-- #BeginEditable "doctitle" --> <title>PTypes: string: manipulation</title><!-- #EndEditable --> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link rel="stylesheet" href="styles.css"></head><body bgcolor="#FFFFFF" leftmargin="40" marginwidth="40"><p><a href="../index.html"><img src="title-20.png" width="253" height="39" alt="C++ Portable Types Library (PTypes) Version 2.0" border="0"></a> <hr size="1" noshade><!-- #BeginEditable "body" --> <p class="hpath"><a href="index.html">Top</a>: <a href="basic.html">Basic types</a>: <a href="string.html">string</a>: Manipulation</p><blockquote> <pre class="lang">#include <ptypes.h><span class="comment">// get/set length and misc.</span>int length(const string& s);char* setlength(string&, int);char* unique(string&);void clear(string& s);bool isempty(const string& s);<span class="comment">// concatenate</span>void concat(string& s, const char* sc, int catlen);<span class="comment">// copy (get substring by position and length)</span>string copy(const string& s, int from [, int cnt ] );<span class="comment">// insert string or character</span>void ins(const char* s1, string& s, int at);void ins(char s1, string& s, int at);void ins(const string& s1, string& s, int at);void ins(const char* s1, int s1len, string& s, int at);<span class="comment">// delete substring</span>void del(string& s, int at [, int cnt ] );<span class="comment">// find substring or character</span>int pos(const char* s1, const string& s);int pos(char s1, const string& s);int pos(const string& s1, const string& s);int rpos(char s1, const string& s);<span class="comment">// compare substring</span>bool contains(const char* s1, const string& s, int at);bool contains(char s1, const string& s, int at);bool contains(const string& s1, const string& s, int at);bool contains(const char* s1, int s1len, const string& s, int at);</pre></blockquote><p><span class="def">int length(const string& s)</span> returns the actual length of the string, not counting the terminating null-symbol.</p><p><span class="def">char* setlength(string&, int)</span> changes the actual length of the string. The content of the original string is preserved, however the content of extra characters added during reallocation is undefined. This function returns a pointer to a unique buffer (i.e. refcount is 1), like function <span class="lang">unique()</span> below. Even if the length of the string is not changing, <span class="lang">setlength()</span> guarantees to make the string unique.</p><p><span class="def">char* unique(string&)</span> makes the string buffer unique, i.e. a new buffer is allocated and data is copied if necessary, so that the reference count after calling this function is guaranteed to be 1. All string manipulation functions call <span class="lang">unique()</span> whenever a modification is made on the string buffer. You may need to call this function explicitly to obtain a character pointer to the buffer; in all other cases reference counting mechanism works transparently.</p><p><span class="def">bool isempty(string&)</span> returns true if the given string is empty. Using this function is preferable to comparing the string with empty string literal "".</p><p><span class="def">clear(string&)</span> makes the given string empty. Using this function is preferable to assigning an empty string literal "".</p><p><span class="def">concat(string& s, const char* sc, int catlen)</span> adds the given buffer <span class="lang">sc</span> of length <span class="lang">catlen</span> to the string object <span class="lang">s</span>. Use operators + and += instead to concatenate characters, null-terminated strings and string objects.</p><p><span class="def">string copy(const string& s, int from [, int cnt ] )</span> returns a substring of <span class="lang">s</span> starting from position <span class="lang">from</span> and containing <span class="lang">cnt</span> characters. If <span class="lang">cnt</span> is omitted, the rest of the string <span class="lang">s</span> starting from position <span class="lang">from</span> is returned.</p><p><span class="def">ins(..., string& s, int at)</span> inserts a character, a null-terminated string, a string object or a buffer with specified length into string object <span class="lang">s</span> at the given position <span class="lang">at</span>. If the position is out of bounds, <span class="lang">ins()</span> does nothing.</p><p><span class="def">del(string& s, int at [, int cnt ] )</span> deletes <span class="lang">cnt</span> characters starting from position <span class="lang">at</span> of the string <span class="lang">s</span>. If <span class="lang">cnt</span> is omitted, the rest of the string starting from <span class="lang">at</span> is deleted.</p><p><span class="def">int pos(..., const string& s)</span> returns the position of the first occurrence of a character, a null-terminated string or a string object (first parameter) in the source string <span class="lang">s</span>, or returns -1 if the substring is not found. Function <span class="lang">rpos()</span> performs reverse-search.</p><p><span class="def">bool contains(..., const string& s, int at)</span> returns true if the given character, null-terminated string or string object (first parameter) equals the substring of <span class="lang">s</span> at the given position <span class="lang">at</span>.</p><p class="seealso">See also: <a href="string.constructors.html">Constructors/destructors</a>, <a href="string.operators.html">Operators</a>, <a href="string.typecasts.html">Typecasts</a>, <a href="string.conversion.html">Conversion</a></p><!-- #EndEditable --><hr size="1"><a href="../index.html" class="ns">PTypes home</a></body><!-- #EndTemplate --></html>⌨️ 快捷键说明
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