[c++ primer plus]使用cout格式化输出

1.进制

cout << _T(" 17.3 修改显示时使用的计数系统") << endl;


int n;


n = 255;


dec(cout); // cout << dec;


cout << "dec : " << n << endl;


oct(cout); // cout << oct;


cout << "oct : " << n << endl;


hex(cout); // cout << hex ;


cout << "hex : " << n << endl;


dec(cout); // 不要影响其它人

[align=left] [/align]
[align=left]2. 输出宽度[/align]


cout << _T(" 17.4 调整字段宽度") << endl;


int w = cout.width(30);


cout << "default field width = " << w << ":" << endl;


cout.width(5);


cout << "N" << ": ";


cout.width(8);


cout << "N * N" << ":" << endl;


for(long i=1; i<=100; i*=10)




{


cout.width(5);


cout << i << ": ";


cout.width(8);


cout << i * i << ":" << endl;


}


cout.width();

3. 填充字符


cout << _T(" 17.5 填充字符") << endl;


cout.fill('*');


int w = cout.width(30);


cout.width(5);


cout << "N" << ": ";


cout.width(8);


cout << "N * N" << ":" << endl;


for(long i=1; i<=100; i*=10)




...{


cout.width(5);


cout << i << ": ";


cout.width(8);


cout << i * i << ":" << endl;


}


cout.width();


cout << endl << endl;

4. 浮点数显示精度


cout << _T(" 17.6 设置浮点数的显示精度") << endl;


float f1 = 23.3232;


float f2 = 1.9 + 8.0 / 9.0;


cout << "f1 = " << f1 << endl;


cout << "f2 = " << f2 << endl;


// 设置精度为2


cout.precision(2);


cout << "f1 = " << f1 << endl;


cout << "f2 = " << f2 << endl;


// 解除设定


cout.precision();





5. setf用法


cout << _T(" 17.7 设置精度为2打印末位的0和小数点") << endl;


float f1 = 23.3232;


float f2 = 1.9 + 8.0 / 9.0;


cout << "f1 = " << f1 << endl;


cout << "f2 = " << f2 << endl;


// 设置精度为2打印末位的0和小数点


cout.setf(ios_base::showpoint);


cout << "f1 = " << f1 << endl;


cout << "f2 = " << f2 << endl;


// 解除设定


cout.setf(ios_base::unitbuf);

6. setf高级用法


cout << _T(" 17.7 setf 高级用法") << endl;


cout.setf(ios_base::showpos);


cout << 63 << endl;


cout.setf(ios_base::uppercase);


cout << "A string" << endl;


cout.setf(ios_base::showbase);


cout << 437 << endl;


cout.setf(ios_base::boolalpha);


cout << true << endl;


cout << false << endl;