这几天我在学习C语言的过程中学到了函数指针这一个概念。我通过查阅各种资料、以及自己举出的几个例子，勉强知道了几个函数指针使用的优点。但是函数指针具体的应用、该在什么时候使用函数指针等方面的概念都很模糊！

所以请教下谁能给个具体的关于函数指针使用的源代码了。

求C预言库函数源代码

搜索《C和C指针》及《C标准库》

typedef int (*Scanner)(void);
static Scanner        Scanners[256];
void SetupLexer(void)
{
    int i;

    for (i = 0; i < END_OF_FILE + 1; i++)
    {
        if (IsLetter(i))
        {
            Scanners[i] = ScanIdentifier;
        }
        else if (IsDigit(i))
        {
            Scanners[i] = ScanNumericLiteral;
        }
        else
        {
            Scanners[i] = ScanBadChar;
        }
    }

    Scanners[END_OF_FILE] = ScanEOF;
    Scanners['\''] = ScanCharLiteral;
    Scanners['"']  = ScanStringLiteral;
    Scanners['+']  = ScanPlus;
    Scanners['-']  = ScanMinus;
    Scanners['*']  = ScanStar;
    Scanners['/']  = ScanSlash;
    Scanners['%']  = ScanPercent;
    Scanners['<']  = ScanLess;
    Scanners['>']  = ScanGreat;
    Scanners['!']  = ScanExclamation;
    Scanners['=']  = ScanEqual;
    Scanners['|']  = ScanBar;
    Scanners['&']  = ScanAmpersand;
    Scanners['^']  = ScanCaret;
    Scanners['.']  = ScanDot;
    Scanners['{']  = ScanLBRACE;
    Scanners['}']  = ScanRBRACE;
    Scanners['[']  = ScanLBRACKET;
    Scanners[']']  = ScanRBRACKET;
    Scanners['(']  = ScanLPAREN;
    Scanners[')']  = ScanRPAREN;
    Scanners[',']  = ScanCOMMA;
    Scanners[';']  = ScanSEMICOLON;
    Scanners['~']  = ScanCOMP;
    Scanners['?']  = ScanQUESTION;
    Scanners[':']  = ScanCOLON;

    if (ExtraKeywords != NULL)
    {
        char *str;
        struct keyword *p;

        FOR_EACH_ITEM(char*, str, ExtraKeywords)
            p = keywords_;
            while (p->name)
            {
                if (strcmp(str, p->name) == 0)
                {
                    p->len = strlen(str);
                    break;
                }
                p++;
            }
        ENDFOR
    }
}