包含文件:
string.h
函数名: strstr
函数原型:
1
|
extern
char
*
strstr
(
char
*str1,
const
char
*str2);
|
语法:
1
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*
strstr
(str1,str2)
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str1: 被查找目标 string expression to search.
str2: 要查找对象 The string expression to find.
返回值:若str2是str1的子串,则返回str2在str1的首次出现的地址;如果str2不是str1的子串,则返回NULL。
例子:
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char
str[]=
"1234xyz"
;
char
*str1=
strstr
(str,
"34"
);
cout << str1 << endl;
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显示的是: 34xyz
1.Copyright 1990 Software Development Systems, Inc.
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char
*
strstr
(
const
char
*s1,
const
char
*s2)
{
int
len2;
if
(!(len2=
strlen
(s2)))
//此种情况下s2不能指向空,否则strlen无法测出长度,这条语句错误
return
(
char
*)s1;
for
(;*s1;++s1)
{
if
(*s1==*s2 &&
strncmp
(s1,s2,len2)==0)
return
(
char
*)s1;
}
return
NULL;
}
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2.Copyright 1986 - 1999 IAR Systems. All rights reserved
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char
*
strstr
(constchar*s1,constchar*s2)
{
int
n;
if
(*s2)
{
while
(*s1)
{
for
(n=0;*(s1+n)==*(s2+n);n++)
{
if
(!*(s2+n+1))
return
(
char
*)s1;
}
s1++;
}
return
NULL;
}
else
return
(
char
*)s1;
}
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3. GCC-4.8.0
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char
*
strstr
(
const
char
*s1,
const
char
*s2)
{
const
char
*p=s1;
const
size_tlen=
strlen
(s2);
for
(;(p=
strchr
(p,*s2))!=0;p++)
{
if
(
strncmp
(p,s2,len)==0)
return
(
char
*)p;
}
return
(0);
}
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