C++ 从cstring函数向string类成员函数迁移2

#include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
  int ptr;
  const char *buf1="BBB", *buf2="bbb";
  ptr=stricmp(buf2,buf1);
  if(ptr>0)
    cout<<"buf2 is greater than buf1"<<endl;
  else if(ptr<0)
    cout<<"buf2 is less than buf1"<<endl;
  else if(ptr==0)
    cout<<"buf2 equals buf1"<<endl;
  return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
  char str[20];
  char c='s';
  strcpy(str,"It\'s a string"); //位置索引从0开始，3即是第4个字符
  char *p=strchr(str,c);
  if(p) //p-str==3 指针减法运算
    cout<<"The character "<<c<<" is at position："<<p-str<<endl;
  else
    cout<<"The character was not found!"<<endl;
  cout<<p<<endl;  //指针已移位，显示为：s a string 
  char *q=strrchr(str,c); //反向查找，位置索引还是从0开始，7即是第8个字符
  if(q) //q-str==7 指针减法运算
    cout<<"The character "<<c<<" is at position："<<q-str<<endl;
  else
    cout<<"The character was not found!"<<endl;
  cout<<q<<endl;  //指针已移位，显示为：string
  return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
  char str[20];
  char s[4]="str";
  strcpy(str,"It\'s a string"); //位置索引从0开始，7即是第8个字符开始 
  char *p=strstr(str,s);
  if(p) //p-str==7 指针减法运算
    cout<<"The substring "<<s<<" is at position："<<p-str<<endl;
  else
    cout<<"The substring was not found!"<<endl;
  cout<<p<<endl;  //指针已移位，显示为：string 
  return 0;
}

#include <iostream>
#include <string>
using namespace std;
int main(void)
{
  string str="It\'s a string.";
  char c='s';
  string::size_type pos;  //或声明为 size_t pos; 如串长不是巨大的话可用int代替 
    //C++函数重载，查找字符或子串用同一函数名
  pos=str.find(c);  //显示：3  正向查找，类似于strchr(str,c) 
  cout<<pos<<endl;
  pos=str.rfind(c); //显示：7  反向查找，类似于strrchr(str,c) 
  cout<<pos<<endl;
  string substr="string";
  pos=str.find(substr); //显示：7
  cout<<pos<<endl;
  pos=str.rfind(substr);  //显示：7
  cout<<pos<<endl;  
  //另可以指定查找位置，返回的还在全串的位置 
  pos=str.find(substr,5); //显示：7
  cout<<pos<<endl;  
  pos=str.find(substr,8); //没找到则返回一个很大的数=Maximum value for size_t 
                            //(实际上就是成员常量string::npos) 声明int型则返回-1 
  cout<<pos<<endl;
  // string::npos 的用法： 
  if (pos != string::npos)  //string::npos 可以用 str.npos 替代 
      cout << "position is：" << pos << endl;  
  else
    cout << "Not found the substring：" + substr;  //此处没找到的原因，设置了开始位置 8 
  return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
  const char *str="(3+3/7)*7 or (4-4/7)*7 = 24";
    cout<<strspn(str,"()")<<endl;   //返回1，str前部连续的有1个字符匹配，即数字3之前的字符数 
    cout<<strspn(str,"37()+-*/")<<endl; //返回9，str前部连续有9个字符匹配，即空格前的字符数 
    cout<<strspn(str,"1234567890")<<endl<<endl; //返回0，字符串str非数字起始 
    cout<<strcspn(str," ")<<endl;   //返回9，str前部9个字符未出现空格 
    cout<<strcspn(str,"+-*/")<<endl;  //返回2，str前部2个字符未出现+-*/
    cout<<strcspn(str,"1234567890")<<endl;  //返回1，即第1个字符不是数字 
  return 0;
}

#include <iostream>
#include <string>
using namespace std;
int main(void)
{
  size_t index,last=0;
  string s="(3+3/7)*7 or (4-4/7)*7 = 24";
  string separator="37()+-*/";
  index=s.find_first_of(separator,last);
  while (index==last++)
    index=s.find_first_of(separator,last);
  cout<<"第一次失配前已匹配的字符数："<<last-1<<endl; //显示9，即最后一个匹配的位置索引+1 
  last=0;
  separator="or";
  do index=s.find_first_not_of(separator,last++); //注意：do-while和while-do的区别 
      while (index==last-1);
  cout<<"第一次匹配前已失配的字符数："<<last-1<<endl; //显示10，即最后一个失配的位置索引+1 
  return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
  const char *str="24 = (3+3/7)*7 or (4-4/7)*7";
  const char *breakset="()^%";  //分界符中至少有一个字符属于str，否则返回NULL
  str=strpbrk(str,breakset); //左(最先出现，此时str=="(3+3/7)*7 or (4-4/7)*7"
  if (str) cout<<str<<endl;  //cout输出NULL，程序会异常退出 
  //用do-while计算除分界符之外的字符数 
    unsigned int cnt=0;
    const char *separator="()+-*/ or";
  do {
    str=strpbrk(str,separator);
    if (str==NULL) break;  //找不到了就中断循环，否则以下操作会退出 
    cout<<cnt<<":"<<str<<endl;  //本行测试用，可去掉 
    str+=strspn(str,separator);
    ++cnt;
  } while(str && *str);
  //cout<<str; //此时str==NULL，此处显示str就会中止退出
  cout<<"\nThere are "<<cnt<<" digits."<<endl;
  return 0;
}

#include <iostream>
#include <string>
using namespace std;
int main(void)
{
  string str="(3+3/7)*7 or (4-4/7)*7";
  string sep="()+-*/ or";
  int index=0,cnt=0;
  for(auto s:str){
    if (sep.find(s)==string::npos)
      cout<<cnt++<<":"<<str.substr(index-1,str.size())<<endl;
    index++;
  }
    //cout<<str; //此时str还是原值，string类的优点之一
  cout<<"\nThere are "<<cnt<<" digits."<<endl;
  return 0;
}

#include <iostream>
#include <cstring>
#include <vector>
using namespace std;
int main(void)
{
  const char *tmp = "hello,Dev-C++";
  char str[20];
  strcpy(str,tmp);
  cout<<"str初值："<<str<<endl;
  char *token = strtok(str,",");
  cout<<token<<endl;
  token=strtok(NULL,","); //str必须包含分界符，否则此行出错
  cout<<token<< endl;
  cout<<"str终值："<<str<<endl; //str被改变了！ 
  //strtok(str,delim)允许同时有多个分界符，但delim中至少有一个字符是str的子串 
  cout<<"\n多个子串可用while循环来分隔"<<endl;
  strcpy(str,tmp); //重新取值
  token=strtok(str,",-");
  while(token!=NULL){
    cout<<token<<endl;
    token=strtok(NULL,",-");
  }
  cout<<"\n把分割出来的子串装入容器中"<<endl;
  strcpy(str,tmp); //重新取值
  vector<string>vect; 
  token=strtok(str,",-");
  while(token!=NULL){
    vect.push_back(token);
    token=strtok(NULL,",-");
  }
  for (auto v:vect) cout<<v<<endl;
  return 0;
}

#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main(void)
{
  vector<string>vect;
  size_t index,last=0;
  string s="Hello,Dev-C++";
  string delim=",-";
  index=s.find_first_of(delim,last);
  while (index!=s.npos){      
    vect.push_back(s.substr(last,index-last));
    last=index+1;
    index=s.find_first_of(delim,last);
    }
    if (s.length()-last>0)
    vect.push_back(s.substr(last));
  for(auto v:vect) cout<<v<<endl;
  return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
  char str[15];
  strcpy(str,"Hello,world!"); 
  cout<<str<<endl;
  char *p=strrev(str);
  cout<<p<<endl; //显示： !dlrow,olleH
  return 0;
}

#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>
using namespace std;
int main(void)
{
  string str="Hello,world!"; 
  reverse(str.begin(),str.end());  //必须包括<algorithm>头文件
  cout<<str<<endl; //显示： !dlrow,olleH
  //或用string::assign + string::rbegin rend
  str.assign(str.rbegin(),str.rend());
  cout<<str<<endl; //显示： Hello,world!
  //reverse()算法也适用于C字符串、字符数组 
    char *c=(char*)str.c_str();
    reverse(c,c+strlen(c));
  cout<<c<<endl; //显示： !dlrow,olleH
  char s[20];
  strcpy(s,c);
  reverse(s,s+strlen(s));
  cout<<s<<endl; //显示： Hello,world!
  return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
  char source[11]="1234567890";
  char target[11];
  swab(source,target,strlen(source));
  cout<<source<<" | "<<target<<endl; //显示：1234567890 | 2143658709
  return 0;
}

#include <iostream>
#include <string>
using namespace std;
int main(void)
{
  string source="1234567890";
  string target;
  target.swap(source);
  cout<<source<<" | "<<target<<endl;
  return 0;
}

#include<iostream>
#include<string>
using namespace std;
string Swab(string);
int main(void)
{
  string str="1234567890";
  cout<<str<<" | "<<Swab(str)<<endl;
  return 0;
}
string Swab(string str)
{
  int i,j=0;
  for (auto&s:str){
    if (j%2==1){
      i=str.at(j-1);
      str.at(j-1)=s;
      s=i;
    }
    j++;
  }
  return str;
}

#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{
    char *endptr;
    char a[] = "123.4567890";
    char b[] = "123.456Hann";
    char c[] = "-123.456E-7";
    cout<<strtol(a,NULL,10)<<endl;
    cout<<a<<endl<<endl;
    cout<<strtol(a,&endptr,10)<<endl;
    cout<<a<<endl; //a未被改变 
    cout<<endptr<<endl<<endl;
    cout<<strtod(b,&endptr)<<endl;
    cout<<b<<endl; //b未被改变 
    cout<<endptr<<endl<<endl;
    cout<<strtod(c,NULL)<<endl;
}

#include <iostream>
#include <sstream>
#include <string>
using namespace std;
template<typename _Type>
_Type str2number(string s)
{
  _Type num;
  stringstream ss;
  ss<<s;
  ss>>num;
  ss.clear();
  return num;
}
int main(void)
{
  string str="1234.56789e-5";
  long double a;
  long int b;
  double c;
  int d;
  a=str2number<long double>(str);
  b=str2number<long int>(str);
  c=str2number<double>(str);
  d=str2number<int>(str);
  cout<<a<<endl;
  cout<<b<<endl;
  cout<<c<<endl;
  cout<<d<<endl;
  return 0;
}

00401028push 14h
  0040102Acall operator new (00401060)
  0040102Fadd esp,4
  00401032mov dword ptr [ebp-8],eax
  00401035mov eax,dword ptr [ebp-8]
  00401038mov dword ptr [ebp-4],eax