1. 使用snprintf格式化字符串
  2. 使用boost::format格式化字符串
  3. 使用stringstream格式化字符串

具体示例

  1. 使用snprintf格式化字符串
#include <stdio.h>
using std::string;
// 准备数据
string haha("haha");
int num = 3;
// 准备格式
string fmt("test string: %s. test number: %d");
char targetString[1024];
// 格式化，并获取最终需要的字符串
int realLen = snprintf(targetString, sizeof(targetString),
							fmt.c_str(), haha.c_str(), num);

参考链接：http://www.cplusplus.com/reference/cstdio/snprintf/

  1. 使用boost::format格式化字符串
#include "boost/format.hpp"
// 准备数据
string haha("haha");
int num = 3;
// 准备格式
boost::format fmt("test string: %s. test number: %d");
// 格式化
fmt % haha % num;
// 获取最终需要的字符串
string targetString = fmt.str();

参考链接：https://www.boost.org/doc/libs/1_70_0/libs/format/example/sample_formats.cpp

  1. 使用stringstream格式化字符串
#include <sstream>
using std::stringstream;
// 准备数据
string haha("haha");
int num = 3;
// 准备根据格式造字符串流
stringstream fmt;                       /* 或者使用 ostringstream */
// 造字符串流
fmt << "test string: " << haha << ". test number: " << num;
// 获取最终需要的字符串
string targetString = fmt.str();

参考链接：http://www.cplusplus.com/reference/ostream/ostream/operator<</

string char*互相转换

1. string to char*

std::string str = "string";
char* chr = const_cast<char*>(str.c_str())


string str = "some string" ;
char *cstr = &str[0];


std::string str = "string";
const char *cstr = str.c_str();

Note that it returns a const char *; you aren’t allowed to change the C-style string returned by c_str(). If you want to process it you’ll have to copy it first:

std::string str = "string";
char *cstr = new char[str.length() + 1];
strcpy(cstr, str.c_str());
// do stuff
delete [] cstr;

Or in modern C++:

std::vector<char> cstr(str.c_str(), str.c_str() + str.size() + 1);
// use &chars[0] as a char*

2. char* to string

方式1：直接赋值：

char c[] = "this is a char array";
const char* t = "const char";
string s = t;
string ss = c;

方式2：https://stackoverflow.com/questions/8438686/convert-char-to-string-c

同理const char*转string：

const char* cc = "this is a const exp";
string s(cc, cc + strlen(cc));

3. char* 和const char*

const char* src = "this is a const exp";
char* ch = const_cast<char*>(src);
const char* dst = static_cast<const char*>(ch);
cout << ch << endl;
cout << dst << endl;

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