程序设计实践阅读摘要[一]

1.1 Names 

    1.Use descriptive names for global, short names for local

        Clarity is often achieved through brievity

    2 Be Constant 

    3 Use active names for functions

        checkoctal Vs isoctal

1.2 Expressions and Statement

    1.Break up complex expressions

        *x += (0xp = (2*k < (n-m) ? c[k+1]: d[k--]));

         Vs

        if (2 * k < n-m)

            *xp = c[k+1];

        else

            *xp = d[k--];

        *x += *xp;

    2.Be carefull with side effects

        scanf("%d %d" &yr, &profit[yr]);

1.3 Consistency and idioms

 

1.4 Functions Macros

    1 Avoid function macros

        parameter appears more than once in the definition might be evaluated more than once

    2 Parenthesize the macro body and arguments 

1.5 Magic Number

    1 Define numbers as constants, not macros

        We can use enum type for C;

        We don't need to apply this rule if the magic number is clearly itself and is used for only once, arraySize for example.

    2 Use the language to calculate the size of an object

        C/C++:

        #define NELEMS(array) (sizeof(array))/sizeof(array[0])

        double buf[1024];

        for(int i = 0; i < NELEMS(buf); i++)

        Java:

        char buf[] = new char[1024];

        for(int i = 0; i < buf; i++)

1.6 Comments

    1 Comment functions and global datas

    2 Don't comment bad code, just rewrite it

    3 Don't contradict the code

        Change the comment accordingly when the code is changed

Supplementary Reading

1 The Elements of Programming Style: Brian Kernighan......

2.Code Complete