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 }
   

5.    1 #include <stdio.h>
      2 #define MAXVAL 10
      3 int queue[MAXVAL];
      4 int front = 0;
      5 int back = 0;
      6 int empty() {
      7     return front == back;
      8 }
      9 int full() {
     10     return (back + 1)%MAXVAL == front;
     11 }
     12 int size() {
     13     return (back - front + MAXVAL) % MAXVAL;
     14 }
     15 void enqueue(int v) {
     16     if(full())
     17         return;
     18     queue[back++] = v;
     19     back = back % MAXVAL;
     20 }
     21 int dequeue() {
     22     int v;
     23     if( empty() )
     24         return 0;
     25     v = queue[front++];
     26     front = front % MAXVAL;
     27     return v;
     28 }
     29 main() {
     30     int i;
     31     for(i = 1; !full(); i++)
     32         enqueue(i);
     33     print("%d\n", size());
     34     while(!empty())
     35         printf("%d\n", dequeue()); 
     36 }
   

6.    1 #include <stdio.h>
      2 #include <ctype.h>
      3 int stricmp(char s[], char t[]) {
      4     int i;
      5     for( i = 0; s[i] != '\0' && t[i] != '\0'; i++)
      6         if(tolower(s[i]) != tolower(t[i]))
      7             break;
      8     return tolower(s[i]) - tolower(t[i]);
      9 }
     10 main() {
     11     char s1[] = { 'a', 'b', 'c', 'd', '\0'};
     12     char s2[] = "ABCD";
     13     char s3[] = "abcde";
     14     int s1s2 = stricmp(s1, s2);
     15     int s2s3 = stricmp(s2, s3);
     16     printf("%s is %s %s\n", s1, s1s2==0 ? "equal to" : s1s2 > 0 ? "great than" : "less than" , s2);
     17     printf("%s is %s %s\n", s2, s2s3==0 ? "equal to" : s2s3 > 0 ? "great than" : "less than" , s3);
     18 }
   

7.    1 #include <stdio.h>
      2 #define INITVAL 5
      3 int count() {
      4     static int c = INITVAL;
      5     return c--;
      6 }
      7 main() {
      8     int i;
      9     while(i = count() )
     10         printf("%d\n", i);
     11 }