读程序，写出程序运行的结果

1.    1 #include <stdio.h>
      2 int dec(int *a) {
      3     return (*a)--;  
      4 }
      5 int inc(int a) {
      6     return a++;
      7 }
      8 main() {
      9     int x = 1, y;
     10     y = dec( &x );
     11     y = inc(x);
     12     printf("%d\n%d\n", x, y);
     13 
     14 }
   

2.    1 #include <stdio.h>
      2 #define min(x,y) (((x)<(y))?(x):(y))
      3 #ifdef EOF
      4 #define square(x)  x*x
      5 #else
      6 #define square(x)  ((x)*(x))
      7 #endif
      8 int main() {
      9     int a = 1, b = 2;
     10     printf("%d\n", square(a+b));
     11     min(a++, b++);
     12     printf("%d\n ", min(a, b));
     13 }
   

3.    1 #include <stdio.h>
      2 void selectsort(int v[], int n) {
      3     int i, j, min, temp;
      4     for( i = 0; i < n-1; i++) {
      5         min = i;
      6         for( j = i + 1; j < n; j++)
      7             if(v[j] < v[min])
      8                 min = j;
      9         temp = v[min];
     10         v[min] = v[i];
     11         v[i] = temp;
     12     }
     13 }
     14 int main() {
     15     int i;
     16     int s[] = { 5, 4, 3, 2, 1};
     17     selectsort(s, 5);
     18     for(i = 0; i < 5; i++)
     19         printf("%3d", s[i]);
     20 }
   

4. 假定int, unsigned是32位的。

      1 #include <stdio.h>
      2 int bitcount(unsigned x) {
      3     int b;
      4     x = ~x;
      5     for(b = 0; x != 0; x >>= 1)
      6         if(x & 1)
      7             b++;
      8     return b;
      9 }
     10 main() {
     11     printf("%d\n%d\n%d\n", bitcount( ~ 0xA), bitcount(017), bitcount(255) );
     12 }