实验5
1 #include<stdio.h>
2 #define N 5
3 4 void input(int x[],int n); 5 void output(int x[],int n); 6 void find_min_max(int x[],int n,int *pmin,int *pmax); 7 8 int main(){ 9 int a[N]; 10 int min,max; 11 12 printf("录入%d个数据:\n",N); 13 input(a,N); 14 15 printf("数据是:\n"); 16 output(a,N); 17 18 printf("数据处理...\n"); 19 find_min_max(a,N,&min,&max); 20 21 printf("输出结果:\n"); 22 printf("min=%d,max=%d\n",min,max); 23 24 return 0; 25 } 26 27 void input(int x[],int n){ 28 int i; 29 30 for(i=0;i<n;++i) 31 scanf("%d",&x[i]); 32 } 33 34 void output(int x[],int n){ 35 int i; 36 37 for(i=0;i<n;++i) 38 printf("%d",x[i]); 39 printf("\n"); 40 } 41 42 void find_min_max(int x[],int n,int *pmin,int *pmax){ 43 int i; 44 45 *pmin=*pmax=x[0]; 46 47 for(i=0;i<n;++i) 48 if(x[i]<*pmin) 49 *pmin=x[i]; 50 else if(x[i]>*pmax) 51 *pmax=x[i]; 52 }

问题1:找到数据中的最大值和最小值
问题2:pmin指向main中的min变量,pmax指向main中的max变量
1 #include<stdio.h> 2 #define N 5 3 4 void input(int x[],int n); 5 void output(int x[],int n); 6 int *find_max(int x[],int n); 7 8 int main(){ 9 int a[N]; 10 int *pmax; 11 12 printf("录入%d个数据:\n",N); 13 input(a,N); 14 15 printf("数据是:\n"); 16 output(a,N); 17 18 printf("数据处理...\n"); 19 pmax=find_max(a,N); 20 21 printf("输出结果:\n"); 22 printf("max=%d\n",*pmax); 23 24 return 0; 25 } 26 27 void input(int x[],int n){ 28 int i; 29 30 for(i=0;i<n;++i) 31 scanf("%d",&x[i]); 32 } 33 34 void output(int x[],int n){ 35 int i; 36 37 for(i=0;i<n;++i) 38 printf("%d",x[i]); 39 printf("\n"); 40 } 41 42 int *find_max(int x[],int n){ 43 int max_index=0; 44 int i; 45 46 for(i=0;i<n;++i) 47 if(x[i]>x[max_index]) 48 max_index=i; 49 return &x[max_index]; 50 51 }

问题1:找到这组数据中的最大值,一个整数
问题2:可以
1 #include<stdio.h> 2 #include<string.h> 3 #define N 80 4 5 int main(){ 6 char s1[N]="Learning makes me happy"; 7 char s2[N]="Learning makes me sleepy"; 8 char tmp[N]; 9 10 printf("sizeof(s1)vs.strlen(s1):\n"); 11 printf("sizeof(s1)=%d\n",sizeof(s1)); 12 printf("strlen(s1)=%d\n",strlen(s1)); 13 14 printf("\nbefore swap:\n"); 15 printf("s1:%s\n",s1); 16 printf("s2:%s\n",s2); 17 18 printf("\nswapping...\n"); 19 strcpy(tmp,s1); 20 strcpy(s1,s2); 21 strcpy(s2,tmp); 22 23 printf("\nafter swap:\n"); 24 printf("s1:%s\n",s1); 25 printf("s2:%s\n",s2); 26 27 return 0; 28 }

问题1:80;计算数组总占用内存字节数;统计字符串有效字符数(不含\0)
问题2:不能替换,因为字符数组名是地址常量,不能直接赋值
问题3:s1和s2的内容完成了交换
#include<stdio.h> 2 #include<string.h> 3 #define N 80 4 5 int main(){ 6 char *s1="Learning makes me happy"; 7 char *s2="Learning makes me sleepy"; 8 char *tmp; 9 10 printf("sizeof(s1)vs.strlen(s1):\n"); 11 printf("sizeof(s1)=%d\n",sizeof(s1)); 12 printf("strlen(s1)=%d\n",strlen(s1)); 13 14 printf("\nbefore swap:\n"); 15 printf("s1:%s\n",s1); 16 printf("s2:%s\n",s2); 17 18 printf("\nswapping...\n"); 19 tmp=s1; 20 s1=s2; 21 s2=tmp; 22 23 printf("\nafter swap:\n"); 24 printf("s1:%s\n",s1); 25 printf("s2:%s\n",s2); 26 27 return 0;

问题1:存储字符串常量首字符L的内存地址;计算指针变量本身占用的内存字节数;从s1指向的首地址开始,逐个总计有效字符个数。
问题2:不能。第一种写法是指针,字符串内容不可改、指针可改指向,第二个数组,数组内容可改,数组名不能被赋值改指向。
问题3:s1,s2两个指针里存的地址值;没有交换。
1 #include<stdio.h> 2 3 int main(){ 4 int x[2][4]={{1,9,8,4},{2,0,4,9}}; 5 int i,j; 6 int *ptr1; 7 int(*ptr2)[4]; 8 9 printf("输出1:使用数组名、下标直接访问二维数组元素\n"); 10 for(i=0;i<2;++i){ 11 for(j=0;j<4;++j) 12 printf("%d",x[i][j]); 13 printf("\n"); 14 } 15 16 printf("\n输出2:使用指针变量ptr1(指向元素)访问\n"); 17 for(ptr1=&x[0][0],i=0;ptr1<&x[0][0]+8;++ptr1,++i){ 18 printf("%d",*ptr1); 19 20 if((i+1)%4==0) 21 printf("\n"); 22 } 23 24 printf("\n输出3:使用指针变量ptr2(指向一维数组)访问\n"); 25 for(ptr2=x;ptr2<x+2;++ptr2){ 26 for(j=0;j<4;++j) 27 printf("%d",*(*ptr2+j)); 28 printf("\n"); 29 } 30 return 0;}

1 #include<stdio.h> 2 #define N 80 3 4 void replace(char*str,char old_char,char new_char); 5 6 int main(){ 7 char text[N]="Programming is difficult or nott,it is a question."; 8 9 printf("原始文本:\n"); 10 printf("%s\n",text); 11 12 replace(text,'i','*'); 13 14 printf("处理后文本:\n"); 15 printf("%s\n",text); 16 17 return 0;} 18 19 void replace(char *str,char old_char,char new_char){ 20 int i; 21 22 while(*str){ 23 if(*str==old_char) 24 *str=new_char; 25 str++; 26 } 27 }

问题1:将原语句中的‘i替换成’*‘
问题2:可以
1 #include<stdio.h> 2 #define N 80 3 char *str_trunc(char *str,char x); 4 int main(){ 5 char str[N]; 6 char ch; 7 while(printf("输入字符串:"),gets(str)!=NULL){ 8 printf("输入一个字符:"); 9 ch=getchar(); 10 getchar(); 11 printf("截断处理...\n"); 12 str_trunc(str,ch); 13 printf("截断处理后的字符串:%s\n\n",str); 14 } 15 return 0;} 16 17 char *str_trunc(char *str,char x){ 18 char *p=str; 19 while(*p){ 20 if(*p==x){ 21 *p='\0'; 22 break; 23 } 24 p++; 25 } 26 return str; 27 }

处理空格
1 #include<stdio.h> 2 #include<string.h> 3 #define N 5 4 5 int check_id(char *str); 6 int main(){ 7 char *pid[N]={"31010120000721656X","3301061996x0203301","53010220051126571","510104199211197977","53010220051126133Y"}; 8 int i; 9 for(i=0;i<N;++i) 10 if(check_id(pid[i])) 11 printf("%s\tTrue\n",pid[i]); 12 else 13 printf("%s\tFalse\n",pid[i]); 14 return 0;} 15 16 int check_id(char *str){ 17 int len=strlen(str); 18 int i; 19 if(len!=18) 20 return 0; 21 22 for(i=0;i<17;i++) 23 if(str[i]<'0'||str[i]>'9') 24 return 0; 25 if((str[17]>='0'&&str[17]<='9')||str[17]=='X') 26 return 1; 27 28 return 0; 29 }

1 #include <stdio.h> 2 #include <string.h> 3 #define N 80 4 void encoder(char *str, int n); // 函数声明 5 void decoder(char *str, int n); // 函数声明 6 7 int main() { 8 char words[N]; 9 int n; 10 11 printf("输入英文文本: "); 12 gets(words); 13 14 printf("输入n: "); 15 scanf("%d", &n); 16 17 printf("编码后的英文文本: "); 18 encoder(words, n); // 函数调用 19 printf("%s\n", words); 20 21 printf("对编码后的英文文本解码: "); 22 decoder(words, n); // 函数调用 23 printf("%s\n", words); 24 25 return 0; 26 } 27 28 29 void encoder(char *str, int n) { 30 int i; 31 for(i=0; i<strlen(str); i++) { 32 if(str[i] >= 'a' && str[i] <= 'z') 33 str[i] = (str[i] - 'a' + n) % 26 + 'a'; 34 else if(str[i] >= 'A' && str[i] <= 'Z') 35 str[i] = (str[i] - 'A' + n ) % 26 + 'A'; 36 } 37 } 38 39 40 void decoder(char *str, int n) { 41 int i; 42 for(i = 0; i < strlen(str); i++) { 43 if(str[i] >='a' && str[i] <= 'z') 44 str[i] = (str[i] - 'a' - n + 26) % 26 + 'a'; 45 else if(str[i] >= 'A' && str[i] <= 'Z') 46 str[i] = (str[i] - 'A' - n + 26) % 26 + 'A'; 47 } 48 }

#include <stdio.h> #include <string.h> int main(int argc, char *argv[]) { int i, j; char *tmp; if (argc < 2) { return 0; } for (i = 1; i < argc - 1; ++i) { for (j = 1; j < argc - i; ++j) { if (strcmp(argv[j], argv[j + 1]) > 0) { tmp = argv[j]; argv[j] = argv[j + 1]; argv[j + 1] = tmp; } } } for (i = 1; i < argc; ++i) { printf("hello, %s\n", argv[i]); } return 0; }

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