C语言 第的八章指针2.ppt

Eg8-10 形参用指针 Eg8-10-3: void copy(from , to) char *from, *to; { while ( *from ! = `\0` ) { *to = *from; from++; to++; } *to = `\0`; } main ( ) {char a[ ]=＂I am a boy!＂; char b[ ]=＂You are a girl!＂; copy(a , b); printf (＂%s\n%s\n＂, a , b); } Eg8-10 形参用指针 Eg8-10-4: void copy(from , to) char *from, *to; { while ( *from ! = `\0` ) { *to = *from; from++; to++; } *to = `\0`; } main ( ) {char a[ ]=＂I am a boy!＂; char b[ ]=＂You are a girl!＂; copy(a , b); printf (＂%s\n%s\n＂, a , b); } while((*to=*from)!=`\0` ) { from++; to++; } Eg8-10 形参用指针 Eg8-10-4: void copy(from , to) char *from, *to; { while ( *from ! = `\0` ) { *to = *from; from++; to++; } *to = `\0`; } main ( ) {char a[ ]=＂I am a boy!＂; char b[ ]=＂You are a girl!＂; copy(a , b); printf (＂%s\n%s\n＂, a , b); } while((*to++=*from++)!= `\0`) ; Eg8-10 形参用指针 Eg8-10-4: void copy(from , to) char *from, *to; { while ( *from ! = `\0` ) { *to = *from; from++; to++; } *to = `\0`; } main ( ) {char a[ ]=＂I am a boy!＂; char b[ ]=＂You are a girl!＂; copy(a , b); printf (＂%s\n%s\n＂, a , b); } while((*to++=*from++) ; 字符串的指针和指向字符串的指针变量 8.4.3字符指针变量与字符数组 1. 区别 数组：存元素 指针变量：存串的首地址 字符指针变量与字符数组 2. 赋值 char *sp; sp = ＂Welcome＂; =首地址 char *sp= ＂Welcome＂; char str[ ]=＂Welcome＂; char str[10]; str = ＂Welcome＂; ? str[ ] = ＂Welcome＂; ? str = {＂Welcome＂}; ? 字符指针变量与字符数组 3. 值 指针变量：可变 数组： 不可变 Eg8-11: main ( ) {char *a =＂I love kitty!＂; a = a + 7; printf(＂%s\n＂, a); } = kitty! Eg8-11-1: main ( ) {char a[ ]=＂I love kitty!＂; a = a + 7; printf(＂%s\n＂, a); } 字符指针变量与字符数组 4. 定义了指针变量，默认定义了数组 Eg8-12: main ( ) { char *a = ＂I love kitty!＂; printf(＂%c\n＂, a[7] ); } a[7]按 *(a+7) 执行 =