C语言可变参数函数使用总结

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C语言可变参数函数使用总结

//ADS1.2下编译使用

void TestFun(char* fmt,...)

{

int ch;

char selch = 0;

va_list ap = NULL;

va_start(ap, fmt);

do

{

selch = *fmt;

if (selch!='%')

{

putchar(*fmt);

}

else

{

selch = *++fmt;

switch(selch)

{

case 'c':

ch = va_arg(ap, int);

printf("%c",ch);

break;

case 'd':

ch = va_arg(ap,int);

printf("%d",ch);

break;

case 'x':

ch = va_arg(ap, int);

printf("%#x",ch);

break;

}

}

++fmt;

}while(*fmt!='');

va_end(ap);

}

//调用

TestFun((char*)"this is %d,%c,%x",1234,'6',0x12345);

//WIN-TC编译通过

#i nclude

/************************************************************

typedef void *va_list;

#define va_start(ap, pARMN) (ap = ...)

#define va_arg(ap, type) (*((type *)(ap))++)

#define va_end(ap)

********************************************************************/

void TestFun(cosnt char* fmt,...)

{

int ch;

long i32value = 0;

char selch = 0;

va_list ap = 0;

va_start(ap, fmt);

do

{

selch = *fmt;

if (selch!='%')

{

putch(*fmt);

}

else

{

selch = *++fmt;

switch(selch)

{

case 'c':

ch = va_arg(ap, int);

printf("%c",ch);

break;

case 'd':

ch = va_arg(ap,int);

printf("%d",ch);

break;

case 'x':

ch = va_arg(ap, int);

printf("%#x",ch);

break;

case 'l':

if(*++fmt== 'd')

{

i32value = va_arg(ap, long);

printf("%ld",i32value);

}

else

{

putch('l');

if(*fmt!=0)

{

putch(*fmt);

}

}

break;

default:

break;

}

}

++fmt;

}while(*fmt!='');

va_end(ap);

}

void main(void)

{

TestFun("this is %d,%c,%x,%ld",1234,'6',0x2345,(long)12345678);

getch();

}

void main(void)

{

TestFun("this is %d,%c,%x,%ld",1234,(char)'6',0x2345,(long)12345678);

getch();

}

上述的example使用宏定义, var_start(ap, pareN),var_arg(ap,type),var_end(ap).

var_start(ap, pareN) //是ap指向第一个变参.

var_arg(ap,type),//返回变参的实际值.

var_end(ap).//是ap指向空指针.

具体的实现,在不同的编译环境下有所不同.

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