C语言函数大全(u开头)

函数名: ultoa

功能: 转换一个无符号长整型数为字符串

用法: char *ultoa(unsigned long value, char *string, int radix);

程序例:

#include

#include

int main( void )

{

unsigned long lnumber = 3123456789L;

char string[25];

ultoa(lnumber,string,10);

printf("string = %s unsigned long = %lu\n",string,lnumber);

return 0;

}

函数名: ungetc

功能: 把一个字符退回到输入流中

用法: int ungetc(char c, FILE *stream);

程序例:

#include

#include

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 = getchar()) != 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)

ungetc(ch, stdin);

printf("i = %d, next char in buffer = %c\n", i, getchar());

return 0;

}

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

#include

#include

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;

}