C語言函數大全(u開頭)

函數名: ultoa

功能: 轉換一個無符號長整型數為字串

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

程式例:

#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;
}

函數名: ungetc

功能: 把一個字元退回到輸入資料流中

用法: int ungetc(char c, FILE *stream);

程式例:

#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;
}

函數名: ungetch

功能: 把一個字元退回到鍵盤緩衝區中

用法: int ungetch(int c);

程式例:

#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;
}