C语言的函数!

内财数模协会 · 发表于 2004-5-10 16:57:03

<

>函数名: ungetch
功能: 把一个字符退回到键盘缓冲区中
用法: int ungetch(int c);
程序例: <

>#include <stdio.h>
#include <ctype.h>
#include <conio.h> <

>int main( void )
{
int i=0;
char ch; puts("Input an integer followed by a char:"); /* read chars until non digit or EOF */
while((ch = getche()) != EOF && isdigit(ch))
 i = 10 * i + ch - 48; /* convert ASCII into int value */ /* if non digit char was read, push it back into input buffer */
if (ch != EOF)
 ungetch(ch); printf("\n\ni = %d, next char in buffer = %c\n", i, getch());
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:57:38

<

>函数名: unixtodos
功能: 把日期和时间转换成DOS格式
用法: void unixtodos(long utime, struct date *dateptr,
struct time *timeptr);
程序例: <

>#include <stdio.h>
#include <dos.h> <

>char *month[] = {"---", "Jan", "Feb", "Mar", "Apr", "May", "Jun",
 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; #define SECONDS_PER_DAY 86400L /* the number of seconds in one day */ struct date dt;
struct time tm; int main(void)
{
unsigned long val; /* get today's date and time */
getdate(&dt);
gettime(&tm);
printf("today is %d %s %d\n", dt.da_day, month[dt.da_mon], dt.da_year); /* convert date and time to unix format (number of seconds since Jan 1, 1970 */
val = dostounix(&dt, &tm);
/* subtract 42 days worth of seconds */
val -= (SECONDS_PER_DAY * 42); /* convert back to dos time and date */
unixtodos(val, &dt, &tm);
printf("42 days ago it was %d %s %d\n",
 dt.da_day, month[dt.da_mon], dt.da_year);
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:57:52

<

>函数名: unlink
功能: 删掉一个文件
用法: int unlink(char *filename);
程序例: <

>#include <stdio.h>
#include <io.h> <

>int main(void)
{
FILE *fp = fopen("junk.jnk","w");
int status; fprintf(fp,"junk"); status = access("junk.jnk",0);
if (status == 0)
 printf("File exists\n");
else
 printf("File doesn't exist\n"); fclose(fp);
unlink("junk.jnk");
status = access("junk.jnk",0);
if (status == 0)
 printf("File exists\n");
else
 printf("File doesn't exist\n");
 return 0;
}

内财数模协会 · 发表于 2004-5-10 16:58:03

<

>函数名: unlock
功能: 解除文件共享锁
用法: int unlock(int handle, long offset, long length);
程序例: <

>#include <io.h>
#include <fcntl.h>
#include <sys\stat.h>
#include <process.h>
#include <share.h>
#include <stdio.h> <

>int main(void)
{
int handle, status;
long length; handle = sopen("c:\\autoexec.bat",O_RDONLY,SH_DENYNO,S_IREAD); if (handle < 0)
{
 printf("sopen failed\n");
 exit(1);
} length = filelength(handle);
status = lock(handle,0L,length/2); if (status == 0)
 printf("lock succeeded\n");
else
 printf("lock failed\n"); status = unlock(handle,0L,length/2); if (status == 0)
 printf("unlock succeeded\n");
else
 printf("unlock failed\n"); close(handle);
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:58:32

<

>函数名: vfprintf
功能: 送格式化输出到一流中
用法: int vfprintf(FILE *stream, char *format, va_list param);
程序例: <

>#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h> <

>FILE *fp; int vfpf(char *fmt, ...)
{
va_list argptr;
int cnt; va_start(argptr, fmt);
cnt = vfprintf(fp, fmt, argptr);
va_end(argptr); return(cnt);
} int main(void)
{
int inumber = 30;
float fnumber = 90.0;
char string[4] = "abc"; fp = tmpfile();
if (fp == NULL)
{
 perror("tmpfile() call");
 exit(1);
} vfpf("%d %f %s", inumber, fnumber, string);
rewind(fp);
fscanf(fp,"%d %f %s", &inumber, &fnumber, string);
printf("%d %f %s\n", inumber, fnumber, string);
fclose(fp); return 0;
}

内财数模协会 · 发表于 2004-5-10 16:58:48

<

>函数名: vfscanf
功能: 从流中执行格式化输入
用法: int vfscanf(FILE *stream, char *format, va_list param);
程序例: <

>#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h> <

>FILE *fp; int vfsf(char *fmt, ...)
{
va_list argptr;
int cnt; va_start(argptr, fmt);
cnt = vfscanf(fp, fmt, argptr);
va_end(argptr); return(cnt);
} int main(void)
{
int inumber = 30;
float fnumber = 90.0;
 char string[4] = "abc"; fp = tmpfile();
if (fp == NULL)
{
 perror("tmpfile() call");
 exit(1);
}
fprintf(fp,"%d %f %s\n",inumber,fnumber,string);
rewind(fp); vfsf("%d %f %s",&inumber,&fnumber,string);
printf("%d %f %s\n",inumber,fnumber,string);
fclose(fp); return 0;
}

内财数模协会 · 发表于 2004-5-10 16:59:04

<

>函数名: vprintf
功能: 送格式化输出到stdout中
用法: int vprintf(char *format, va_list param);
程序例: <

>#include <stdio.h>
#include <stdarg.h> <

>int vpf(char *fmt, ...)
{
va_list argptr;
int cnt; va_start(argptr, format);
cnt = vprintf(fmt, argptr);
va_end(argptr); return(cnt);
} int main(void)
{
int inumber = 30;
float fnumber = 90.0;
char *string = "abc"; vpf("%d %f %s\n",inumber,fnumber,string); return 0;
}

内财数模协会 · 发表于 2004-5-10 16:59:28

<

>函数名: vscanf
功能: 从stdin中执行格式化输入
用法: int vscanf(char *format, va_list param);
程序例: <

>#include <stdio.h>
#include <conio.h>
#include <stdarg.h> <

>int vscnf(char *fmt, ...)
{
va_list argptr;
int cnt; printf("Enter an integer, a float, and a string (e.g. i,f,s,)\n");
va_start(argptr, fmt);
cnt = vscanf(fmt, argptr);
va_end(argptr); return(cnt);
} int main(void)
{
int inumber;
float fnumber;
char string[80]; vscnf("%d, %f, %s", &inumber, &fnumber, string);
printf("%d %f %s\n", inumber, fnumber, string); return 0;
}

内财数模协会 · 发表于 2004-5-10 16:59:42

<

>函数名: vsprintf
功能: 送格式化输出到串中
用法: int vsprintf(char *string, char *format, va_list param);
程序例: <

>#include <stdio.h>
#include <conio.h>
#include <stdarg.h> <

>char buffer[80]; int vspf(char *fmt, ...)
{
va_list argptr;
int cnt; va_start(argptr, fmt);
cnt = vsprintf(buffer, fmt, argptr);
va_end(argptr); return(cnt);
} int main(void)
{
int inumber = 30;
float fnumber = 90.0;
char string[4] = "abc"; vspf("%d %f %s", inumber, fnumber, string);
printf("%s\n", buffer);
return 0;
}

内财数模协会 · 发表于 2004-5-10 16:59:50

<

>函数名: vsscanf
功能: 从流中执行格式化输入
用法: int vsscanf(char *s, char *format, va_list param);
程序例: <

>#include <stdio.h>
#include <conio.h>
#include <stdarg.h> <

>char buffer[80] = "30 90.0 abc"; int vssf(char *fmt, ...)
{
va_list argptr;
int cnt; fflush(stdin); va_start(argptr, fmt);
cnt = vsscanf(buffer, fmt, argptr);
va_end(argptr); return(cnt);
} int main(void)
{
int inumber;
float fnumber;
char string[80]; vssf("%d %f %s", &inumber, &fnumber, string);
printf("%d %f %s\n", inumber, fnumber, string);
return 0;
}

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