断言 assert(表达式) 相关概念

news/2024/9/28 5:22:18 标签: null, 编译器, 测试, c
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class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">来自：color: navy; font-family: 黑体; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA;" lang="EN-US">ccolor: navy; font-family: 黑体; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA;">和指针.P342

class="MsoNormal" style="margin: 0cm 0cm 0pt;">

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">断言就是声明某种东西应该为真。color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">ANSI C color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">实现了一个color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">assertcolor: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">宏࿰c;它在调试程序时很有用。它的原型如下所示：color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">void assert( int expression );

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">当它被执行时࿰c;这个宏对表达式参数进行class="tags" href="/tags/CeShi.html" title=测试>测试。如果它的值为假࿰c;它就向标准错误打印一条诊断信息并终止程序。这条信息的格式是由class="tags" href="/tags/BianYiQi.html" title=编译器>编译器定义的࿰c;但它将包含这个表达式所在的源文件的名字以及断言所在的行号。如果表达式为真࿰c;它不打印任何东西࿰c;程序继续执行。用这种方法使用断言使调试程序变得更容易࿰c;因为一旦出现错误࿰c;程序就会停止。而且࿰c;这条错误提示信息会准确地提示了症状出现的地点。color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">这个宏提供了一种方便的方法࿰c;对应该为真的东西进行检验。例如：如果一个函数必须使用一个不能为color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">NULLcolor: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">的指针参数进行调用࿰c;那么函数可以用断言验证这个值：“color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">assert( value != NULL );color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">”color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;"> color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">如果函数错误的接受了一个color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">NULLcolor: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">参数࿰c;程序就会打印一条类似下面形式的信息：color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">Assertion failed: != NULL, file.c line 214

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">当程序被完整的class="tags" href="/tags/CeShi.html" title=测试>测试完毕之后࿰c;你可以在编译时通过定义color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">NDEGUG color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">消除所有的断言。你可以使用color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">-DNDEBUGcolor: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">class="tags" href="/tags/BianYiQi.html" title=编译器>编译器命令行选项color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;"> color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">或者color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;"> color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">在源文件中头文件color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">assert.hcolor: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">被包含之前增加下面这个定义color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">:

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">#define NDEBUG

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">当color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">NDEBUGcolor: #333399; font-family: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">被定义之后࿰c;预处理器将丢弃所有的断言࿰c;这样就消除了这方面的开销࿰c;而不必从源文件中把所有的断言实际删除。color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US">

class="MsoNormal" style="margin: 0cm 0cm 0pt;">color: #333399; font-family: Verdana; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: Arial;" lang="EN-US"> 

class="MsoNormalTable" style="margin: auto auto auto 5.4pt; border-collapse: collapse; mso-border-alt: dashed silver .5pt; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-border-insideh: .5pt dashed silver; mso-border-insidev: .5pt dashed silver;" border="1" cellspacing="0" cellpadding="0">
ckground: #f8f8f8; padding-bottom: 0cm; width: 509.15pt; padding-top: 0cm; height: 69.25pt; mso-border-alt: dashed silver .5pt; border: silver 1pt dashed;" width="679">

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">#include<stdio.h>

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">#include<string.h>

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: #333399; font-family: Verdana;" lang="EN-US">//#define NDEBUG

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">#include<assert.h>

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">void my_strcopy( char * dest,cerun: yes;">  char * src )

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">{

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">cerun: yes;">    assert( srccerun: yes;">  != NULL );

class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 14.75pt; line-height: 10pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.96;">color: purple; font-family: Verdana;" lang="EN-US">assert( dest != NULL );

class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 14.75pt; line-height: 10pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.96;">color: purple; font-family: Verdana;" lang="EN-US">assert( strlen(src) >= strlen(dest) );

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 14.75pt; line-height: 10pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.96;">color: purple; font-family: Verdana;" lang="EN-US">while( (*dest++ = *src++) != '/0' );

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">}

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">int main()

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">{

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">cerun: yes;">    char str1[] = "0123456789";

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">cerun: yes;">    char str2[] = "abcdefghijk";

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 14.75pt; line-height: 10pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.96;">color: purple; font-family: Verdana;" lang="EN-US">printf("cerun: yes;">    color: purple; font-family: 宋体; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">原始字符串：color: purple; font-family: Verdana;" lang="EN-US">/n%s/n%s/n",str1,str2);

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">cerun: yes;">    my_strcopy( str1, str2 );

class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 14.75pt; line-height: 10pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.96;">color: purple; font-family: Verdana;" lang="EN-US">printf("color: purple; font-family: 宋体; mso-ascii-font-family: Verdana; mso-hansi-font-family: Verdana;">拷贝后的字符串：color: purple; font-family: Verdana;" lang="EN-US">/n%s/n%s/n",str1,str2);

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US"> 

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">cerun: yes;">    getchar();

class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 14.75pt; line-height: 10pt; mso-line-height-rule: exactly; mso-char-indent-count: 1.96;">color: purple; font-family: Verdana;" lang="EN-US">return 0;

class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 10pt; mso-line-height-rule: exactly;">color: purple; font-family: Verdana;" lang="EN-US">}

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