怎么做呢？想了好久了。都没做出来。。。

const char * strstr （ const char * str1, const char * str2 );
      char * strstr （       char * str1, const char * str2 ); 

locate substring

returns a pointer to the first occurrence of str2 in str1, or a null pointer if there str2 is not part of str1.

the matching process does not include the terminating null-characters.


parameters
str1 
c string to be scanned. 
str2 
c string containing the sequence of characters to match. 

return value
a pointer to the first occurrence in str1 of any of the entire sequence of characters specified in str2, or a null pointer if the sequence is not present in str1.

portability
in c, this function is declared as:
char * strstr （ const char *, const char * );

instead of the two overloaded versions provided in c++.


example
/* strstr example */
#include <stdio.h>
#include <string.h>

int main （)
{
  char str[] ="this is a simple string";
  char * pch;
  pch = strstr （str,"simple");
  strncpy （pch,"sample",5);
  puts （str);
  return 0;
}
 
this example searches for the "simple" substring in str and replaces that word for "sample".
output:

this is a sample string 

example
/* strstr example */
#include <stdio.h>
#include <string.h>

int main （)
{
  char str[] ="this is a simple string";
  char * pch;
  pch = strstr （str,"simple");
  strncpy （pch,"sample",5);
  puts （str);
  return 0;
}