#include
#include
#define ARR 50
int main()
{
    int counter,i,c;
    double arr[ARR],sum,value;
    char out_str[10]="%.";
        counter=0;
        sum=0.0;
        printf("Please enter value (-1 to quit):");
        scanf("%lf",&value);
        while(value!=-1)
        {
                arr[counter]=value;
                printf("Please enter value (-1 to quit):");
                scanf("%lf",&value);
                sum =value;
                counter  ;
                
        }
        printf("How many digits after decimal place ?=>");
        scanf("%s",&out_str[2]);
        strcat(&out_str[2],"lf");
        printf("\n%d values were entered\n",counter);
        printf("These values are:\n");
        i=0;
        while (i
Output:
Please enter value (-1 to quit):12.3
Please enter value (-1 to quit):23.3
Please enter value (-1 to quit):34.4
Please enter value (-1 to quit):35.5
Please enter value (-1 to quit):56.7
Please enter value (-1 to quit):45.7
Please enter value (-1 to quit):34.6
Please enter value (-1 to quit):23.5
Please enter value (-1 to quit):-1
How many digits after decimal place ?=>3    8 values were entered
These values are:
12.30023.30034.40035.50056.70045.700
34.60023.500請按任意鍵繼續 . . .    他的問題就是輸出的數字都都沒空格,我希望各個輸出的數字要有空格,但我又要保留(How many digits after decimal place ?=>)這個功能該怎ㄇ改呢?~求助各位大大幫忙了感激不盡~^^
    
        

您好: 12.30023.30034.40035.50056.70045.700 34.60023.500請按任意鍵繼續 . . . 您是說這裡的數字要空格嗎?如果是的話 把這行printf(out_str,arr[i]);改成下面這樣. printf("%d ",out_str,arr[i]);

這位大大這樣雖然會空格但他都變成不同的數字了說~ 我要他輸出為 12.300 23.300 34.400 35.500 56.700 45.700 34.600 23.500

沒注意看到還有一個變數@@ 把這行printf(out_str,arr[i]);改成下面這樣. printf("%c%d ",out_str,arr[i]); 發表人 - supman 於 2005/04/11 08:31:21

dear tai1688: 可以用sprintf產生需要的輸出格式字串(out_str)，再交由printf輸出：

char out_str[10];
int  digit;    printf("How many digits after decimal place ?=>");
scanf("%d", &digit);    sprintf(out_str, "%%.ß ", digit);
digit = 3, 則out_str會是 %.3f_ (underbar表示space)
顯示就按照你的方式即可
printf(out_str, arr[i]);

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcstdlib/html/vclrf_iomanip_Setw.asp 希望這個可以滿足你的要求; 另外下面的code是我測試的 你可以試試

#include 
#pragma hdrstop
#include 
#include 
#include 
//---------------------------------------------------------------------------    #pragma argsused
int main()
{
        cout << setw(20)<<123456<