文档介绍：分类函数,(intch) 若ch是字母('A'-'Z','a'-'z')返回非0值,否则返回0intisalnum(intch) 若ch是字母('A'-'Z','a'-'z')或数字('0'-'9')                    返回非0值,否则返回0intisascii(intch) 若ch是字符(ASCII码中的0-127)返回非0值,trl(intch) 若ch是作废字符(0x7F)或普通控制字符(0x00-0x1F)                    返回非0值,否则返回0intisdigit(intch) 若ch是数字('0'-'9')返回非0值,否则返回0intisgraph(intch) 若ch是可打印字符(不含空格)(0x21-0x7E)返回非0值,否则返回0intislower(intch) 若ch是小写字母('a'-'z')返回非0值,否则返回0intisprint(intch) 若ch是可打印字符(含空格)(0x20-0x7E)返回非0值,否则返回0intispunct(intch) 若ch是标点字符(0x00-0x1F)返回非0值,否则返回0intisspace(intch) 若ch是空格(''),水平制表符('\t'),回车符('\r'),                    走纸换行('\f'),垂直制表符('\v'),换行符('\n')                    返回非0值,否则返回0intisupper(intch) 若ch是大写字母('A'-'Z')返回非0值,否则返回0intisxdigit(intch)若ch是16进制数('0'-'9','A'-'F','a'-'f')返回非0值,                    否则返回0inttolower(intch) 若ch是大写字母('A'-'Z')返回相应的小写字母('a'-'z')inttoupper(intch) 若ch是小写字母('a'-'z')返回相应的大写字母('A'-'Z')数学函数,、、、     abs(inti)                   返回整型参数i的绝对值double cabs(plexznum)     返回复数znum的绝对值double fabs(doublex)                返回双精度参数x的绝对值long   labs(longn)                  返回长整型参数n的绝对值double  exp(doublex)                返回指数函数ex的值doublefrexp(doublevalue,int*eptr)  返回value=x*2n中x的值,n存贮在eptr中doubleldexp(doublevalue,intexp);   返回value*2exp的值double  log(doublex)                返回logex的值doublelog10(doublex)                返回log10x的值double  pow(doublex,doubley)       返回xy的值doublepow10(intp)                   返回10p的值double sqrt(doublex)                返回+√x的值double acos(doublex)                返回x的反余弦cos-1(x)值,x为弧度double asin(doublex)                返回x的反正弦sin-1(x)值,x为弧度double atan(doublex)                返回x的反正切tan-1(x)值,x为弧度doubleatan2(doubley,doublex)       返回y/x的反正切tan-1(x)值,y的x为弧度double  cos(doublex)                返回x的余弦cos(x)值,x为弧度double  sin(doublex)                返回x的正弦sin(x)值,x为弧度double  tan(doublex)                返回x的正切tan(x)值,x为弧度double cosh(doublex)                返回x的双曲余弦cosh(x)值,x为弧度double sinh(doublex)                返回x的双曲正弦sinh(x)值,x为弧度double