在C/C++中进行不区分大小写的子字符串搜索的最快方法？

该main功能是:

int main(void)
{
        char * needle="hello";
        char haystack[1024];
        int i;

        for(i=0;i

它经过适当修改以测试两种实现方式.我注意到,当我打字时,我在init_stristr通话中离开了,但它不应该改变太多.bench只是一个简单的shell脚本:

#!/bin/bash
function bc_calc()
{
        echo $(echo "scale=4;$1" | bc)
}
time="/usr/bin/time -p"
prog="$1"
accum=0
runs=10
for a in $(jot $runs 1 $runs)
do
        echo -n "run $a... "
        t=$($time $prog 2>&1| grep user | awk '{print $2}')
        echo "time = $t"
        accum=$(bc_calc "$accum+$t")
done

echo -n "average user time over $runs runs = "
echo $(bc_calc "$accum/$runs")

        

          
        

      

    

  

  
  

    

      

        Nitin Chhabr..
         7
      
      
您可以使用StrStrI函数查找字符串中第一次出现的子字符串.比较不区分大小写.不要忘记包括它的标题 -  Shlwapi.h.看看这个:http://msdn.microsoft.com/en-us/library/windows/desktop/bb773439(v = vs.85).aspx


1> freespace..：
您发布的代码大约快一半strcasestr.


$ gcc -Wall -o my_stristr my_stristr.c
steve@solaris:~/code/tmp
$ gcc -Wall -o strcasestr strcasestr.c 
steve@solaris:~/code/tmp
$ ./bench ./my_stristr > my_stristr.result ; ./bench ./strcasestr > strcasestr.result;
steve@solaris:~/code/tmp
$ cat my_stristr.result 
run 1... time = 6.32
run 2... time = 6.31
run 3... time = 6.31
run 4... time = 6.31
run 5... time = 6.32
run 6... time = 6.31
run 7... time = 6.31
run 8... time = 6.31
run 9... time = 6.31
run 10... time = 6.31
average user time over 10 runs = 6.3120
steve@solaris:~/code/tmp
$ cat strcasestr.result 
run 1... time = 3.82
run 2... time = 3.82
run 3... time = 3.82
run 4... time = 3.82
run 5... time = 3.82
run 6... time = 3.82
run 7... time = 3.82
run 8... time = 3.82
run 9... time = 3.82
run 10... time = 3.82
average user time over 10 runs = 3.8200
steve@solaris:~/code/tmp


该main功能是:


int main(void)
{
        char * needle="hello";
        char haystack[1024];
        int i;

        for(i=0;i

它经过适当修改以测试两种实现方式.我注意到,当我打字时,我在init_stristr通话中离开了,但它不应该改变太多.bench只是一个简单的shell脚本:

#!/bin/bash
function bc_calc()
{
        echo $(echo "scale=4;$1" | bc)
}
time="/usr/bin/time -p"
prog="$1"
accum=0
runs=10
for a in $(jot $runs 1 $runs)
do
        echo -n "run $a... "
        t=$($time $prog 2>&1| grep user | awk '{print $2}')
        echo "time = $t"
        accum=$(bc_calc "$accum+$t")
done

echo -n "average user time over $runs runs = "
echo $(bc_calc "$accum/$runs")

        

2> Nitin Chhabr..：
您可以使用StrStrI函数查找字符串中第一次出现的子字符串.比较不区分大小写.不要忘记包括它的标题 -  Shlwapi.h.看看这个:http://msdn.microsoft.com/en-us/library/windows/desktop/bb773439(v = vs.85).aspx