String formatting

In the process of programming , You need to convert numeric variables into string variables in a certain format , Here are some basic format conversion statements ：

Format currency

string.Format("{0:C}",0.2);  //￥0.20（ Under English operating system ：＄0.20）

By default, this method formats two decimal places after the decimal point , If you need to keep one or more , You can specify the number of digits , Use the rounding method when intercepting .

string.Format("{0:C1}",0.25);  //￥0.2
string.Format("{0:C1}",0.26);  //￥0.3

Number formatting

1. Format fixed digit decimal digits

string.Format("{0:D3}",23);   //023
string.Format("{0:D3}",2343);   //2343

This method can format numbers into fixed digits , And it only supports plastic surgery . The specified fixed number of digits indicates the minimum number of digits required in the result string , When the specified fixed number of digits is less than the number of digits of the number itself , The result string is the number itself .

2. Use commas to divide numbers and specify the number of digits after the decimal point

string.Format("{0:N}",230869.55);   //230869.55
string.Format("{0:N1}",230869.55);   //230869.5

By default, this method formats two decimal places after the decimal point , If you need to keep one or more , You can specify the number of digits , Use the rounding method when intercepting .

3. Format as percentage

string.Format("{0:P}",0.23256);   //23.26%
string.Format("{0:P1}",0.23255);   //23.3%

By default, this method formats two decimal places after the decimal point , If you need to keep one or more , You can specify the number of digits , Use the rounding method when intercepting .

Place holder

1. Zero placeholder

string.Format("{0:0000.00}",23243.214);   //023
string.Format("{0:0000.00}",243.215);   //2343

This can be done by “ Place on digit 0” To format numbers , If the target number has a number on the corresponding digit, the number will be retained , If there is no number, use 0 fill . amount to “ Fixed digit decimal digits ” The enhanced . rounding .
2. Digital placeholders

string.Format("{0:####.##}",23243.214);   //023
string.Format("{0:####.##}",243.215);   //2343

The method and “ Zero placeholder ” The effect is similar to , Use “#” To identify the form of numbers , If the target number has a number on the corresponding digit, the number will be retained , If there is no number, omit the digit .
3. Space placeholder

string A = string.Format("{0,-25}", " Align left , Not enough space ");
A += "( end )";

Date formatting

string.Format("{0:d}", DateTime.Now);    // 2022/6/11
string.Format("{0:g}", DateTime.Now);    // 2022/6/11 15:58
string.Format("{0:G}", DateTime.Now);    // 2022/6/11 15:58:16

string.Format("{0:D}", DateTime.Now);    // 2022 year 6 month 11 Japan , Saturday 
string.Format("{0:f}", DateTime.Now);    // 2022 year 6 month 11 Japan , Saturday  15:58
string.Format("{0:F}", DateTime.Now);    // 2022 year 6 month 11 Japan , Saturday  15:58:16

string.Format("{0:m}", DateTime.Now);    // 6 month 11 Japan 
string.Format("{0:t}", DateTime.Now);    // 15:58
string.Format("{0:T}", DateTime.Now);    // 15:58:16

---

The above string formatting statement can convert non string variables into strings in a certain format , The conversion effect cannot be achieved for variables that are strings .