第八章：指针06
让编程改变世界
Change the world by program
字符指针作函数参数
出错了：关于a[]和*a的一些区别！ [codesyntax lang="c"]#include <stdio.h>
void main()
{
void copy_string( char *from, char *to );
char *a = "I am a teacher.";
char b[] = "You are a student."; //此处应该定义为char b[] = "You are a student.";
//区别两者反汇编代码并解释其意义
//谈谈五个区!
printf("String a = %snString b = %sn", a, b);
printf("copy string a to string b:n");
copy_string(a, b);
printf("nString a = %snString b = %sn", a, b);
}
void copy_string( char *from, char *to )
{
for( ; *from != '�'; from++,to++)
{
*to = *from;
}
*to = '�';
}
[/codesyntax]
优化：对 copy_string 函数还可作简化
方法一
[codesyntax lang="c"]#include <stdio.h>
void main()
{
void copy_string( char *from, char *to );
char *a = "I am a teacher.";
char b[] = "You are a student.";
printf("String a = %snString b = %sn", a, b);
printf("copy string a to string b:n");
copy_string(a, b);
printf("nString a = %snString b = %sn", a, b);
}
void copy_string( char *from, char *to )
{
while( (*to = *from) != '�' )
{
to++;
from++;
}
}
[/codesyntax]
方法二
[codesyntax lang="c"]#include <stdio.h>
void main()
{
void copy_string( char *from, char *to );
char *a = "I am a teacher.";
char b[] = "You are a student.";
printf("String a = %snString b = %sn", a, b);
printf("copy string a to string b:n");
copy_string(a, b);
printf("nString a = %snString b = %sn", a, b);
}
void copy_string( char *from, char *to )
{
while( (*to++ = *from++) != '�')
{
;
}
}
[/codesyntax]
方法三
[codesyntax lang="c"]#include <stdio.h>
void main()
{
void copy_string( char *from, char *to );
char *a = "I am a teacher.";
char b[] = "You are a student.";
printf("String a = %snString b = %sn", a, b);
printf("copy string a to string b:n");
copy_string(a, b);
printf("nString a = %snString b = %sn", a, b);
}
void copy_string( char *from, char *to )
{
while( *from != '�' )
{
*to++ = *from++;
}
*to = '�';
}
[/codesyntax]
方法四
[codesyntax lang="c"]#include <stdio.h>
void main()
{
void copy_string( char *from, char *to );
char *a = "I am a teacher.";
char b[] = "You are a student.";
printf("String a = %snString b = %sn", a, b);
printf("copy string a to string b:n");
copy_string(a, b);
printf("nString a = %snString b = %sn", a, b);
}
void copy_string( char *from, char *to )
{
while( *to++ = *from++ )
{
; // '�' == 0
}
}
[/codesyntax]
方法五
[codesyntax lang="c"]#include <stdio.h>
void main()
{
void copy_string( char *from, char *to );
char *a = "I am a teacher.";
char b[] = "You are a student.";
printf("String a = %snString b = %sn", a, b);
printf("copy string a to string b:n");
copy_string(a, b);
printf("nString a = %snString b = %sn", a, b);
}
void copy_string( char *from, char *to )
{
for( ; *to++ = *from++; )
{
;
}
}
[/codesyntax]
方法六
[codesyntax lang="c"]#include <stdio.h>
void main()
{
void copy_string( char *from, char *to );
char *a = "I am a teacher.";
char b[] = "You are a student.";
printf("String a = %snString b = %sn", a, b);
printf("copy string a to string b:n");
copy_string(a, b);
printf("nString a = %snString b = %sn", a, b);
}
void copy_string( char from[], char to[] )
{
char *p1, *p2;
p1 = from;
p2 = to;
while( (*p2++ = *p1++) != '�' )
{
;
}
}
[/codesyntax]
[buy] 获得所有教学视频、课件、源代码等资源打包 [/buy]
[Downlink href='http://kuai.xunlei.com/d/LHAPZBNXYNES']视频下载[/Downlink]