实验5
实验任务1
实验代码
#include <stdio.h>
#define N 4
int main()
{
int x[N] = {1, 9, 8, 4};
int i;
int *p;
for (i = 0; i < N; ++i)
printf("%d", x[i]);
printf("\n");
for (p = x; p < x + N; ++p)
printf("%d", *p);
printf("\n");
p = x;
for (i = 0; i < N; ++i)
printf("%d", *(p + i));
printf("\n");
p = x;
for (i = 0; i < N; ++i)
printf("%d", p[i]);
printf("\n");
return 0;
}
#include <stdio.h>
int main() {
int x[2][4] = {{1, 9, 8, 4}, {2, 0, 4, 9}};
int i, j;
int *p;
int (*q)[4];
for(i = 0;i < 2; i++) {
for(j = 0;j < 4; j++)
printf("%d", x[i][j]);
printf("\n");
}
for(p = &x[0][0], i = 0;p < &x[0][0] + 8; ++p, ++i)
{
printf("%d", *p);
if((i + 1) % 4 == 0)
printf("\n");
}
for(q = x;q < x + 2; ++q) {
for(j = 0;j < 4; ++j)
printf("%d", *(*q + j));
printf("\n");
}
return 0;
}
实验结论
实验任务2
实验代码
#include <stdio.h>
#include <string.h>
#define N 80
int main() {
char s1[] = "Learning makes me happy";
char s2[] = "Learning makes me sleepy";
char tmp[N];
printf("sizeof(s1) vs. strlen(s1): \n");
printf("sizeof(s1) = %d\n", sizeof(s1));
printf("strlen(s1) = %d\n", strlen(s1));
printf("\nbefore swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
printf("\nswapping...\n");
strcpy(tmp, s1);
strcpy(s1, s2);
strcpy(s2, tmp);
printf("\nafter swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
return 0;
}
#include <stdio.h>
#include <string.h>
#define N 80
int main() {
//char *s1 = "Learning makes me happy";
char *s1;
s1 = "Learning makes me happy";
char *s2 = "Learning makes me sleepy";
char *tmp;
printf("sizeof(s1) vs. strlen(s1): \n");
printf("sizeof(s1) = %d\n", sizeof(s1));
printf("strlen(s1) = %d\n", strlen(s1));
printf("\nbefore swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
printf("\nswapping...\n");
tmp = s1;
s1 = s2;
s2 = tmp;
printf("\nafter swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
return 0;
}
实验结论
回答问题
task2_1:
1.数组s1的大小是24，sizeof计算的是大小包括'0'，strlen计算的是长度
2.不能，不能像这样直接声明一个没有确定大小的数组。字符串赋值只能一位一位的。
3.交换了
task2_2:
1.指针s1存放的是字符数组的首地址，sizeof计算的一个指针的大小，strlen计算的是长度
2.能
3.交换的是指针，储存单元中的内容没有交换
实验任务3
实验代码
#include <stdio.h>
void str_cpy(char *target, const char *source);
void str_cat(char *str1, char *str2);
int main() {
char s1[80], s2[20] = "1984";
str_cpy(s1, s2);
puts(s1);
str_cat(s1, " Animal Farm");
puts(s1);
return 0;
}
void str_cpy(char *target, const char *source) {
while (*target++ = *source++);
}
void str_cat(char *str1, char *str2) {
while (*str1)
str1++;
while (*str1++ = *str2++);
}
实验结论
实验任务4
实验代码
#include <stdio.h>
#define N 80
int func(char *);
int main() {
char str[80];
while (gets(str) != NULL) {
if (func(str))
printf("yes\n");
else
printf("no\n");
}
return 0;
}
int func(char *str) {
char *begin, *end;
begin = end = str;
while (*end)
end++;
end--;
while (begin < end) {
if (*begin != *end)
return 0;
else {
begin++;
end--;
}
}
return 1;
}
实验结论
实验任务5
实验代码
#include <stdio.h>
#define N 80
void func(char *);
int main() {
char s[N];
while (scanf("%s", s) != EOF) {
func(s);
puts(s);
}
return 0;
}
void func(char *str)
{
int i;
char *p1, *p2, *p;
p1 = str;
while (*p1 == '*')
p1++;
p2 = str;
while (*p2)
p2++;
p2--;
while (*p2 == '*')
p2--;
p = str;
i = 0;
while (p < p1) {
str[i] = *p;
p++;
i++;
}
while (p <= p2) {
if (*p != '*') {
str[i] = *p;
i++;
}
p++;
}
while (*p != '\0') {
str[i] = *p;
p++;
i++;
}
str[i] = '\0';
}
实验结论
实验任务6
实验代码
#include <stdio.h>
#include <string.h>
void sort(char *name[], int n);
int main() {
char *course[4] = {"C Program",
"C++ Object Oriented Program",
"Operating System",
"Data Structure and Algorithms"};
int i;
sort(course, 4);
for (i = 0; i < 4; i++)
printf("%s\n", course[i]);
return 0;
}
void sort(char *name[], int n) {
int i, j;
char *tmp;
for (i = 0; i < n - 1; ++i)
for (j = 0; j < n - 1 - i; ++j)
if (strcmp(name[j], name[j + 1]) > 0) {
tmp = name[j];
name[j] = name[j + 1];
name[j + 1] = tmp;
}
}
#include <stdio.h>
#include <string.h>
void sort(char *name[], int n);
int main() {
char *course[4] = {"C Program",
"C++ Object Oriented Program",
"Operating System",
"Data Structure and Algorithms"};
int i;
sort(course, 4);
for (i = 0; i < 4; i++)
printf("%s\n", course[i]);
return 0;
}
void sort(char *name[], int n) {
int i, j, k;
char *tmp;
for (i = 0; i < n - 1; i++) {
k = i;
for (j = i + 1; j < n; j++)
if (strcmp(name[j], name[k]) < 0)
k = j;
if (k != i) {
tmp = name[i];
name[i] = name[k];
name[k] = tmp;
}
}
}
实验结论
回答问题
交换的是内存中字符串的储存位置
实验任务7
实验代码
#include <stdio.h>
#include <string.h>
#define N 5
int check_id(char *str);
int main() {
char * pid[N] = {"31010120000721656X",
"330106199609203301",
"53010220051126571",
"510104199211197977",
"53010220051126133Y"};
int i;
for(i = 0;i < N; i++)
if(check_id(pid[i]))
printf("%s\tTrue\n", pid[i]);
else
printf("%s\tFalse\n", pid[i]);
return 0;
}
int check_id(char *str) {
int len = strlen(str);
int i;
if(len != 18) return 0;
for(i = 0;i < len; i++) {
char x = *(str + i);
if(i == 17) {
if((x >= '0' && x <= '9') || x =='X') continue ;
else return 0;
}
else {
if(x >= '0' && x <= '9') continue ;
else return 0;
}
}
return 1;
}
实验结论
实验任务8
实验代码
#include <stdio.h>
#include <string.h>
#define N 80
void encoder(char *s);
void decoder(char *s);
int main() {
char words[N];
printf("输入英文文本：");
gets(words);
printf("编码后的英文文本：");
encoder(words);
printf("%s\n", words);
printf("对编码后的英文文本解码：");
decoder(words);
printf("%s\n", words);
return 0;
}
void encoder(char *s) {
int i, len;
len = strlen(s);
for(i = 0;i < len; i++) {
char x;
x = *(s + i);
if((x >= 'a' && x <= 'z') || (x >= 'A' && x <= 'Z')) {
if(x == 'z') *(s + i) = 'a';
else if(x == 'Z') *(s + i) = 'A';
else *(s + i) = x + 1;
}
}
}
void decoder(char *s) {
int i, len;
len = strlen(s);
for(i = 0;i < len; i++) {
char x;
x = *(s + i);
if((x >= 'a' && x <= 'z') || (x >= 'A' && x <= 'Z')) {
if(x == 'a') *(s + i) = 'z';
else if(x == 'A') *(s + i) = 'Z';
else *(s + i) = x - 1;
}
}
}
实验结论
