מבוא לתכנות ולמדעי המחשב בשפת C/שיעורי חזרה
שיעור חזרה ראשון
עריכה#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int add(int a, int b) {
if(b==0)
return a;
return add(a+1,b-1);
}
int pow1(int a, int n) {
if(n==0)
return 1;
return a*pow1(a,n-1);
}
int pow2(int a, int n) {
if(n==1)
return a;
int t = pow2(a,n/2);
if(n%2 == 0)
return t*t;
return t*t*a;
}
int find(char c, char *str, int from, int to) {
int i;
for(i=from; i<=to; ++i)
if(str[i] == c)
return i;
return -1;
}
int evaluateRec(char *str, int from, int to) {
int i = find('+',str,from,to);
if(i != -1)
return evaluateRec(str,from,i-1)+evaluateRec(str,i+1,to);
i = find('X',str,from,to);
if(i != -1)
return evaluateRec(str,from,i-1) * evaluateRec(str,i+1,to);
return atoi(str+from);
}
int evaluate(char* str) {
return evaluateRec(str,0,strlen(str)-1);
}
int main() {
printf("%d\n",add(3,4));
printf("%d\n",pow1(2,5));
printf("%d\n",pow2(2,5));
printf("%d\n",evaluate("445X23+23X21"));
return 0;
}
שיעור חזרה שני
עריכהisPalindrome
עריכהint isPalindrome(char *str) {
int n=0;
while(str[n] != '\0')
++n;
int i;
for(i=0; i<n/2; ++i)
if(str[i] != str[n-1-i])
return 0;
return 1;
}
int main() {
char *array[] = {"ere","wewew","neveroddoreven","gfgf","neveroddorevenw"};
int n = sizeof(array)/sizeof(char*);
int i;
for(i=0; i<n; ++i) {
if(isPalindrome(array[i]))
printf("%s is a palindrom\n",array[i]);
else
printf("%s is *not* a palindrom\n",array[i]);
}
return 0;
}
b4 max
עריכהint b4max(int *array, int n) {
int i,max,b4;
b4 = max = array[0];
for(i=1; i<n; ++i)
if(array[i] > max) {
b4 = max;
max = array[i];
} else
if(array[i] > b4)
b4 = array[i];
return b4;
}
int main() {
int array[] = {3,9,1,2,3,7,11,45,12,1};
int n = sizeof(array)/sizeof(int);
printf("%d \n",b4max(array,n));
return 0;
}
draw memory.. what is the output
עריכהint main() {
int array[10];
int i;
for(i=0; i<10; ++i)
array[i] = i+1;
int *p1 = array, *p2 = array+9;
int **pp = &p1;
for(i=0; i<5; ++i) {
printf("%d \n",**pp);
++p1;
--p2;
if(pp == &p1)
pp = &p2;
else
pp = &p1;
}
return 0;
}
draw memory.. what is the output
עריכהstruct A {
int data;
};
struct B {
struct A a;
struct A *ptr;
};
int main() {
struct B array[10];
int i;
for(i=0; i<9; ++i) {
array[i].a.data = i;
array[i].ptr = & (array[i+1].a);
}
array[9].a.data = 9;
for(i=0; i<9; ++i)
printf("%d \n",(array[i].ptr)->data);
return 0;
}
random
עריכה#include <stdio.h>
#include <stdlib.h>
void swap(int *p1, int *p2) {
int tmp = *p1;
*p1 = *p2;
*p2 = tmp;
}
int main() {
int array[10];
int i;
for(i=0; i<10; ++i)
array[i] = i+1;
for(i=9; i>=0; --i) {
int j = rand()%(i+1);
printf("%d \n",array[j]);
swap(array+j,array+i);
}
return 0;
}