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36 lines
1.0 KiB
HTML
36 lines
1.0 KiB
HTML
<h1>字符函数 - isalnum</h1>
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<p>原型：extern int isalnum(int c);</p>
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<p>用法：#include <ctype.h></p>
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<p>功能：判断字符c是否为字母或数字</p>
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<p>说明：当c为数字0-9或字母a-z及A-Z时，返回非零值，否则返回零。</p>
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举例：<pre>
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// isalnum.c
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#include <syslib.h>
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#include <ctype.h>
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main()
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{
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int c;
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clrscr(); // clear screen
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c='a';
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printf("%c:%s\n",c,isalnum(c)?"yes":"no");
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c='7';
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printf("%c:%s\n",c,isalnum(c)?"yes":"no");
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c='@';
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printf("%c:%s\n",c,isalnum(c)?"yes":"no");
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getchar();
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return 0;
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}
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</pre>相关函数：<a href="isalpha.html">isalpha</a>,<a href="isdigit.html">isdigit</a>,<a href="isxdigit.html">isxdigit</a>,<a href="iscntrl.html">iscntrl</a>,<a href="isgraph.html">isgraph</a>,<a href="isprint.html">isprint</a>,<a href="ispunct.html">ispunct</a>,<a href="isspace.html">isspace</a>
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