c语言程序设计8.4指针与字符串PPT.ppt

指针和字符串
常用的字符串处理函数
字符串的指针表示
字符数组和字符指针
char *name[4]={“Wang”, “Li”, “Zhao”, “Jin”};
char ** pp = name;
printf(“%s\n”, *pp);
printf(“%c”, **pp);
name[0]
name
“Wang”
name[1]
“Li”
name[2]
“Zhao”
name[3]
“Jin”
*pp
pp
输出:
Wang
W
char *name[4]={“Wang”, “Li”, “Zhao”, “Jin”};
char ** pp = name;
printf(“%s\n”, *pp);
输出:Wang
name[0]
name
“Wang”
name[1]
“Li”
name[2]
“Zhao”
name[3]
“Jin”
*pp
pp
pp = pp + 2;
printf(“%s\n”, *pp);
printf(“%c”, **pp);
Zhao
Z
char *name[4]={“Wang”, “Li”, “Zhao”, “Jin”};
char ** pp;
for(pp=name;pp<name+4; pp++)
printf(“%s ”, *pp);
输出:
Wang Li Zhao Jin
name[0]
name
“Wang”
name[1]
“Li”
name[2]
“Zhao”
name[3]
“Jin”
*pp
pp
char *name[4]={“Wang”, “Li”, “Zhao”, “Jin”};
char ** pp;
for(pp=name;pp<name+4; pp++)
printf(“%c ”, **pp);
name[0]
name
“Wang”
name[1]
“Li”
name[2]
“Zhao”
name[3]
“Jin”
*pp
pp
输出:
W L Z J
char *name[4]={“Wang”, “Li”, “Zhao”, “Jin”};
char ** pp;
for(pp=name;pp<name+4; pp++)
printf(“%s ”, *pp+1);
输出:
ang i hao in
name[0]
name
“Wang”
name[1]
“Li”
name[2]
“Zhao”
name[3]
“Jin”
*pp
pp
指针和函数
指针作为函数的返回值
函数 match 在一个字符串中寻找某个字符,如找到,返回第一次找到的该字符在字符串的位置;否则,返回空指针NULL。
char *match(char c, char *s)
{ while(*s != '\0')
if(*s == c) return(s); /* 返回指针*/
else s++;
return(0);
}
#include <>
main( )
{ char *cp="ABCDEFGHIJK";
printf("%s\n", match(’B', cp));
printf("%s\n", match(’H',cp));
printf("%s\n", match(’a',cp));
}
输出:BCDEFGHIJK
HIJK
字符串复制函数 strcpy(s1, s2), 返回s1
char *strcpy(char *s1, char *s2)
{ char *ss=s1;
while ( *s1++ = *s2++);
return ss;
}
void strcpy(char *s1, char *s2)
{
while ( *s1++ = *s2++);
}

可以定义一个指向函数的指针变量,用来存放某一函数的起始地址,这就意味着此指针变量指向该函数。例如:
int (*p)(int,int);
定义p是指向函数的指针变量,它可以指向类型为整型且有两个整型参数的函数。p的类型用int (*)(int,int)表示