In C language, integer constants can be expressed in the following three forms:

1, a decimal integer, is the normal expression of the digital form of daily contact. Such as 123,-120;

2, an octal integer, represented by a number beginning with 0. For example, 0 123 stands for octal number 123, that is, (123)8, and its value is 1*82+2*8 1+3*80, which is equal to decimal number 83. -0 1 1 means octal number-1 1, that is, decimal number -9.

3. Hexadecimal integer, represented by a number beginning with 0x. For example, 0x 123 represents hexadecimal number 123, that is, (123) 16, and its value is1*162+2 *16. -0x 12 equals the decimal number-18.

Extended data:

Real constant

In C language, real constants can only be expressed in decimal. It has two forms: decimal form and exponential form.

1, decimal form

It consists of symbols, numbers from 0 to 9 and decimal points. There cannot be numbers before and after the decimal point (it cannot be omitted at the same time). Such as:-1.85, 0.24, .426,-1 1.

2. Exponential form

It consists of decimal number plus rank code mark e or e and rank code. Its general form is aEn. Where a is a decimal number, n is a decimal integer ("+"can be omitted when n is a positive number), and its value is a× 10? .

For example, 1.236e+2 means1.236x10? .

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