实验五
task1-1
#include<stdio.h> #define N 4 int main() { int x[N] = {1, 9, 8, 4}; int i; int *p; // 方式1：通过数组名和下标遍历输出数组元素 for (i = 0; i < N; ++i) printf("%d", x[i]); printf("\n"); // 方式2：通过指针变量遍历输出数组元素 （写法1） for (p = x; p < x + N; ++p) printf("%d", *p); printf("\n"); // 方式2：通过指针变量遍历输出数组元素（写法2） p = x; for (i = 0; i < N; ++i) printf("%d", *(p + i)); printf("\n"); // 方式2：通过指针变量遍历输出数组元素（写法3） p = x; for (i = 0; i < N; ++i) printf("%d", p[i]); printf("\n"); return 0; }
task1-2
#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"); } //指针 for(q=x;q<x+2;++q) { for(j=0;j<4;++j) printf("%d",*(*q+j)); printf("\n"); } return 0; }
tas2-1
#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; }
1、23，sizeof计算类型或变量所占空间的大小，单位为字节，计算时包括‘\0’。strlen计算字符串长度，不包括‘\0’。
2、不能，s1的长度未定义
3、交换了
task2-2
#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; 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; }
1、指针变量s1中存放了字符串“Learning makes me happy”。sizeof(s1)计算的是指针变量s1所占的字节数。strlen(s1)统计的是字符串的长度。
2、可以。
3、地址。没有。
task3
#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++) ; }
task4
#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; }
task5
#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'; }
task6-1
#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; } }
task6-2
#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; } } }
交换的是指针变量的值
task7
#include <stdio.h> #include <string.h> #define N 5 int check_id(char *str); // 函数声明 int main() { char *pid[N] = {"31010120000721656X", "330106199609203301", "53010220051126571", "510104199211197977", "53010220051126133Y"}; int i; for (i = 0; i < N; ++i) if (check_id(pid[i])) // 函数调用 printf("%s\tTrue\n", pid[i]); else printf("%s\tFalse\n", pid[i]); return 0; } int check_id(char *str){ char *p,*j; int cnt=0; p=str; j=str; while(*p){ cnt++; p++; } if(cnt==18){ while(*j){ if(*j>47&&*j<58||*j==88) j++; else return 0; } return 1; } else return 0; }
task8
#include<stdio.h> #define N 80 void encoder(char *s); // 函数声明 void decoder(char *s); // 函数声明 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); // 函数调用 printf("%s\n", words); printf("对编码后的英文文本解码: "); decoder(words); // 函数调用 printf("%s\n", words); return 0; } /*函数定义 功能：对s指向的字符串进行编码处理 编码规则： 对于a~z或A~Z之间的字母字符，用其后的字符替换; 其中，z用a替换，Z用A替换 其它非字母字符，保持不变 */ void encoder(char *s) { while(*s){ if((*s>=65&&*s<90)||(*s>=97&&*s<122)) *s+=1; else if(*s==90){*s=65;} else if(*s==122){*s=97;} s++; } } /*函数定义 功能：对s指向的字符串进行解码处理 解码规则： 对于a~z或A~Z之间的字母字符，用其前面的字符替换; 其中，a用z替换，A用Z替换 其它非字母字符，保持不变 */ void decoder(char *s) { while(*s){ if((*s>65&&*s<=97)||(*s>97&&*s<=122)) {*s-=1;} else if(*s==65){*s=90;} else if(*s==97){*s=122;} s++; } }
