C++ 比较两个 char* 是否相等
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Comparing two char* for equality
提问by Bryan Wong
Possible Duplicate:
What is the proper function for comparing two C-style strings?
可能的重复：
比较两个 C 样式字符串的正确函数是什么？
My match condition doesn't work! Can someone advise how to compare to C-style strings?
我的匹配条件不起作用！有人可以建议如何与 C 风格的字符串进行比较吗？
void saveData(string line, char* data){
char *testString = new char[800];
char *stpr;
int i=0;
bool isData=false;
char *com = data;
strcpy(testString,line.c_str());
stpr = strtok(testString, ",");
while (stpr != NULL) {
string temp = stpr;
cout << temp << " ===== " << data << endl;
Even though tempand datamatch, the following condition doesn't work:
即使temp和data匹配，以下条件也不起作用：
if (stpr==data) {
isData = true;
}
Not sure if this helps. The SaveData()function is called from the function below:
不确定这是否有帮助。该SaveData()函数是从下面的函数调用的：
void readFile(char* str){
string c="", line, fileName="result.txt", data(str);
ifstream inFile;
inFile.open(fileName.c_str());
resultlist.clear();
if(inFile.good()){
while(!inFile.eof()){
getline(inFile, line);
if(line.find(data)!=string::npos){
cout << line << endl;
}
saveData(line, str);
}
inFile.close();
}
}
回答by NPE
回答by Coding Mash
This condition wont work because the ==operator is not overloaded for char*.
此条件不起作用，因为==运算符没有为 重载char*。
if(stpr==data)
{
isData = true;
}
Use this instead.
改用这个。
if (strcmp(stpr, data) == 0)
{
isData = true ;
}
strcmp()returns 0if both the cstrings are equal. Make sure that both the cstrings you are matching hold some legal memory and are null terminated at the end.
strcmp()0如果两个 cstring 相等，则返回。确保您匹配的两个 cstring 都保存了一些合法内存，并且在末尾以 null 结尾。
Edit:
编辑：
To avoid any sort of hassle and bugs, it is advisable not to use raw char*and use std::stringinstead. So better make them strings and compare them.
为避免任何麻烦和错误，建议不要使用 raw而是char*使用std::string。所以最好把它们做成字符串并比较它们。
std::string data ; //passed or declared as string
std::string stpr ;
.....
//Do some work.
if (stpr == data)
//do work here
This approach would save you a lot of troubles.
这种方法可以为您省去很多麻烦。
回答by Rahul Tripathi
You are trying to compare two char*. YOu can try using strcmp(stpr, data)for checking the conditions.
您正在尝试比较两个 char*。您可以尝试使用strcmp(stpr, data)来检查条件。
Better use it like
更好地使用它
if(strcmp(stpr, data)==0){..}
