index-1 后 变量index的值并没有变化 只是表达式的值变了
#include <stdio.h>
int main (void)
{
    int index = 0, convertedNumber[64], numberToConvert;
    printf ("Number to be converted:");
    scanf ("%i", &numberToConvert);
    do
    {
        convertedNumber[index] = numberToConvert % 2;
        index ++;
        numberToConvert = numberToConvert / 2;
    }
    while (numberToConvert != 0);

    printf ("numberToConvert = ");
    for (; index-1 >= 0; index--)
    {
        printf("%d", convertedNumber [index-1]);
    }
    printf ("\n");
    return 0;
}

你试试这个
#include <stdio.h>
int main (void)
{
int index = 0, convertedNumber[64], numberToConvert,a;
printf ("Number to be converted:");
scanf ("%d", &numberToConvert);
do
{
  convertedNumber[index] = numberToConvert % 2;
  index ++;
  numberToConvert = numberToConvert / 2;
}
while (numberToConvert != 0);
a=index-1;
for (; a >= 0; a--)
{
   printf ("%d", convertedNumber [a]);
}
printf ("\n");
return 0;
}

for (; index-1 >= 0; index--)
初始值表达式是空？~
我发现我看过初始值是空意味着什么但是不记得了……