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Python重写C语言程序100例--Part6

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【程序41】
题目:学习static定义静态变量的用法   
1.程序分析:
2.程序源代码:
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# python没有这个功能了,只能这样了:)
def varfunc():
    var = 0
    print ‘var = %d‘ % var
    var += 1
if __name__ == ‘__main__‘:
    for i in range(3):
        varfunc()

# attribut of class
# 作为类的一个属性吧
class Static:
    StaticVar = 5
    def varfunc(self):
        self.StaticVar += 1
        print self.StaticVar

print Static.StaticVar
a = Static()
for i in range(3):
    a.varfunc()

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题目:学习使用auto定义变量的用法
1.程序分析:      
2.程序源代码:
没有auto关键字,使用变量作用域来举例吧
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num = 2
def autofunc():
    num = 1
    print ‘internal block num = %d‘ % num
    num += 1
for i in range(3):
    print ‘The num = %d‘ % num
    num += 1
    autofunc()
    

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【程序43】
题目:学习使用static的另一用法。   
1.程序分析:
2.程序源代码:
有一个static变量的用法,python是没有,演示一个python作用域使用方法
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class Num:
    nNum = 1
    def inc(self):
        self.nNum += 1
        print ‘nNum = %d‘ % self.nNum

if __name__ == ‘__main__‘:
    nNum = 2
    inst = Num()
    for i in range(3):
        nNum += 1
        print ‘The num = %d‘ % nNum
        inst.inc()

 

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【程序45】
题目:学习使用register定义变量的方法。
1.程序分析:
2.程序源代码:
没有register关键字,用整型变量代替
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tmp = 0
for i in range(1,101):
    tmp += i
print ‘The sum is %d‘ % tmp


 

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【程序46】
题目:宏#define命令练习(1)   
1.程序分析:
2.程序源代码:
没有C语言的宏,就这么写了
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TRUE = 1
FALSE = 0
def SQ(x):
    return x * x
print ‘Program will stop if input value less than 50.‘
again = 1
while again:
    num = int(raw_input(‘Please input number‘))
    print ‘The square for this number is %d‘ % (SQ(num))
    if num >= 50:
        again = TRUE
    else:
        again = FALSE


 

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题目:宏#define命令练习(2)
1.程序分析:            
2.程序源代码:
#include "stdio.h"
#define exchange(a,b) { \ /*宏定义中允许包含两道衣裳命令的情形,此时必须在最右边加上"\"*/
            int t;            t=a;            a=b;            b=t;           }‘
这个宏定义python不支持
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def exchange(a,b):
    a,b = b,a
    return (a,b)

if __name__ == ‘__main__‘:
    x = 10
    y = 20
    print ‘x = %d,y = %d‘ % (x,y)
    x,y = exchange(x,y)
    print ‘x = %d,y = %d‘ % (x,y)


 

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【程序48】
题目:宏#define命令练习(3)   
1.程序分析:
2.程序源代码:
#define LAG >
#define SMA <
#define EQ ==
#include "stdio.h"
void main()
{ 
	int i=10;
	int j=20;
	if(i LAG j)
		printf("\40: %d larger than %d \n",i,j);
	else if(i EQ j)
		printf("\40: %d equal to %d \n",i,j);
	else if(i SMA j)
		printf("\40:%d smaller than %d \n",i,j);
	else
		printf("\40: No such value.\n");
}
不知道如何用python实现类似的功能
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if __name__ == ‘__main__‘:
    i = 10
    j = 20
    if i > j:
        print ‘%d larger than %d‘ % (i,j)
    elif i == j:
        print ‘%d equal to %d‘ % (i,j)
    elif i < j:
        print ‘%d smaller than %d‘ % (i,j)
    else:
        print ‘No such value‘
    


 

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【程序49】
题目:#if #ifdef和#ifndef的综合应用。
1. 程序分析:
2.程序源代码:
#include "stdio.h"
#define MAX
#define MAXIMUM(x,y) (x>y)?x:y
#define MINIMUM(x,y) (x>y)?y:x
void main()
{ 
	int a=10,b=20;
#ifdef MAX
	printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#else
	printf("\40: The lower one is %d\n",MINIMUM(a,b));
#endif
#ifndef MIN
	printf("\40: The lower one is %d\n",MINIMUM(a,b));
#else
	printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#endif
#undef MAX
#ifdef MAX
	printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#else
	printf("\40: The lower one is %d\n",MINIMUM(a,b));
#endif
#define MIN
#ifndef MIN
	printf("\40: The lower one is %d\n",MINIMUM(a,b));
#else
	printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#endif
}
这个还是预处理的用法,python不支持这样的机制,演示lambda的使用。
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MAXIMUM = lambda x,y :  (x > y) * x + (x < y) * y
MINIMUM = lambda x,y :  (x > y) * y + (x < y) * x

if __name__ == ‘__main__‘:
    a = 10
    b = 20
    print ‘The largar one is %d‘ % MAXIMUM(a,b)
    print ‘The lower one is %d‘ % MINIMUM(a,b)