C + + string Find_first of implementation

One: Before the implementation of the first find_first_of sister function

(1) find_first_of (string &str, Size_type index = 0):

Finds the first character in a string that matches a character in Str and returns its position. search starts from index forward and returns String::npos if not found

(2) find_first_not_of (CString &str, Size_type index = 0):

Finds the first character in a string that does not match the character in Str and returns its position. The search starts from index forward . If you don't find it, return to String::nops.

(3) find_last_of (CString &str, Size_type index = 0):

Finds the last character in a string that matches a character in Str and returns its position. search starts at the reverse of index . If you don't find it, return to String::nops.

(4) find_last_not_of (CString &str, Size_type index = 0):

Finds the last character in a string that does not match the character in Str and returns its position. search starts at the reverse of index . If you don't find it, return to String::nops.

(5) Total (3) and (4) lookup from the reverse of index, also equivalent to (1) and (2) in the first

Two: Manually implement the Find_first_of () function

(1) int mystring::find_first_of (const char* str,size_t index)

int mystring::find_first_of (const char* str,size_t index)    {        int tmp_len = strlen (str), J;        size_t flag,mymin = Ini_max;        for (j=0;j<tmp_len;j++)        {            flag =-1;            for (size_t i=index;i<strlength;i++)            {                if (str[j] = = P_str[i])                {                    flag = i;                    break;                }            }            indexs[j] = flag;            if (flag! =-1)            {                mymin = mymin<flag?mymin:flag;            }        } For        (j=0;j<tmp_len;j++)//        {//            if (indexs[j]!=-1)//                min = min<indexs[j]?min:indexs[j] ;//        }        if (mymin = = Ini_max)        {            return-1;//            mymin = -1;//           cout << "----1----" < < mymin << ",,,,";        }        return mymin;    }

(2) int mystring::find_first_of (const char ch,size_t index)

int mystring::find_first_of (const char ch,size_t index)    {        int J;        size_t flag =-1;        for (size_t i=index;i<strlength;i++)        {            if (ch = = P_str[i])            {                flag = i;                break;            }        }        return flag;    }

(3) int mystring::find_first_of (const mystring& str,size_t index)

   int mystring::find_first_of (const mystring& str,size_t index)    {        int J;        size_t flag,mymin = Ini_max;        for (j=0;j<str.strlength;j++)        {            flag =-1;            for (size_t i=index;i<strlength;i++)            {                if (str[j] = = P_str[i])                {                    flag = i;                    break;                }            }            if (flag! =-1)            {                mymin = mymin<flag?mymin:flag;            }        }        if (mymin = = Ini_max)        {            return-1;        }        return mymin;    }

Three: Look back at the run example of the string class itself

(1) First look at the results, and then to the code

(2) Main.cpp code

#include <string> #include <iostream>using namespace Std;int main () {string Strfir ("ABCEDCFCA"), Strsec ("    ABC abc abddef ");    cout << "1:" << strfir.find ("a") << Endl; Finds the first character in a string that matches a character in Str and returns its position.    Search from index forward, if not found return string::npos cout << "2:" << strfir.find_first_of ("DCE", 0) << endl;//any one character Finds the first character in a string that does not match the character in Str and returns its position. The search starts from index forward.    If not found, return to String::nops cout << "3:" << strfir.find_first_not_of ("AC", 2) << Endl; Finds the last character in a string that matches a character in Str and returns its position. Search starts at the reverse of index.    If not found, return to String::nops cout << "4:" << strfir << strfir.find_last_of ("Ca", 4) << Endl;    cout << "4:" << strfir << strfir.find_last_of ("Ca", 9) << Endl; Finds the last character in a string that does not match the character in Str and returns its position. The search starts at index.    If not found, return to String::nops cout << "3:" << strfir << strfir.find_last_not_of ("AC") << Endl; return 0;}

Four: Sentiment

(1) Student age can not be wasted like this, need to learn to learn, self-study;

(2) Weekly understanding of a type of STL, do not too much, analysis and understanding of the implementation of an STL container, estimated to take at least two days;

(3) Every week to do the experiment must be advanced, you can not write a word to the present ~ ~ ~ ~ Hands must have the ability to do.

C + + string Find_first of implementation