使用 ifstream 读取带逗号的 .txt 文件
Using ifstream to read .txt file with comma
基于 ifstream 我正在使用以下函数读取 filename.txt 文件
//reading from text file
static std::vector<double> vec;
double a[18]; //values got read from txt file
int i = 0;
void readDATA()
{
double value;
std::ifstream myFile;
myFile.open("filename.txt", std::ios::app);
if (myFile.is_open())
{
std::cout << "File is open." << std::endl;
while (myFile >> value)
{
vec.push_back(value);
std::cout << "value is " << value << std::endl;
a[i] = value;
std::cout << "a" << i << "=" << a[i] << std::endl;
i = i + 1;
}
myFile.close();
}
else
std::cout << "Unable to open the file";
}
它工作正常
以下是 filename.txt 文件的内容:
0 0 40 45 15
0 1 40 -45 10
0 0 180 90 15
能否请你帮我修改函数,这样我就可以读取同一个 .txt 文件,元素之间用逗号分隔 ?
您想阅读数字后跟冒号吗?
定义将处理此“任务”的 class:
struct Number
{
double value;
operator double() const { return value; }
};
std::istream& operator >>(std::istream& is, Number& number)
{
is >> number.value;
// fail istream on anything other than ',' or whitespace
// end reading on ',' or '\n'
for (char c = is.get();; c = is.get()) {
if (c == ',' or c == '\n')
break;
if (std::isspace(c))
continue;
is.setstate(std::ios_base::failbit);
break;
}
return is;
}
然后在您的代码中 - 将 double value;
替换为 Number value;
类似这样的你可以试试
std::string data;
while(std::getline(myFile, data)) {
std::istringstream ss(data);
std::string token;
while(std::getline(ss, token, ','))
double d = std::stod(token);
}
基于 ifstream 我正在使用以下函数读取 filename.txt 文件
//reading from text file
static std::vector<double> vec;
double a[18]; //values got read from txt file
int i = 0;
void readDATA()
{
double value;
std::ifstream myFile;
myFile.open("filename.txt", std::ios::app);
if (myFile.is_open())
{
std::cout << "File is open." << std::endl;
while (myFile >> value)
{
vec.push_back(value);
std::cout << "value is " << value << std::endl;
a[i] = value;
std::cout << "a" << i << "=" << a[i] << std::endl;
i = i + 1;
}
myFile.close();
}
else
std::cout << "Unable to open the file";
}
它工作正常 以下是 filename.txt 文件的内容:
0 0 40 45 15
0 1 40 -45 10
0 0 180 90 15
能否请你帮我修改函数,这样我就可以读取同一个 .txt 文件,元素之间用逗号分隔 ?
您想阅读数字后跟冒号吗?
定义将处理此“任务”的 class:
struct Number
{
double value;
operator double() const { return value; }
};
std::istream& operator >>(std::istream& is, Number& number)
{
is >> number.value;
// fail istream on anything other than ',' or whitespace
// end reading on ',' or '\n'
for (char c = is.get();; c = is.get()) {
if (c == ',' or c == '\n')
break;
if (std::isspace(c))
continue;
is.setstate(std::ios_base::failbit);
break;
}
return is;
}
然后在您的代码中 - 将 double value;
替换为 Number value;
类似这样的你可以试试
std::string data;
while(std::getline(myFile, data)) {
std::istringstream ss(data);
std::string token;
while(std::getline(ss, token, ','))
double d = std::stod(token);
}