C程序设计第十章习题

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3. 向文件中输入字符串

代码：

#include "stdio.h"void main() {FILE *file;file = fopen("test.txt", "w");char str[200];gets(str);int i = 0;while(str[i]) {if(str[i] >= 'a' && str[i] <= 'z') str[i] = str[i] + 'A' - 'a';i++;}fputs(str, file);fclose(file);
}

输出结果：

4.合并字符串，并且写入新文件C中。

代码：

#include "stdio.h"void init();
char *read(char *file_name, char *str);
char *merge(char *A, char *B, char *C);
void sort(char *str);
void write(char *file_name, char *str);void main() {init();char A[200];read("A.txt", A);char B[200];read("B.txt", B);char C[400];merge(A, B, C);printf("%s\n", C);sort(C);printf("%s\n", C);write("C.txt", C);
}void init() {FILE *afile, *bfile;afile = fopen("A.txt", "w");bfile = fopen("B.txt", "w");char A[200] = "afjfaojfoqjefqpoqhf";char B[200] = "ajiafdhiophpahofhap";fputs(A, afile);fputs(B, bfile);fclose(afile);fclose(bfile);
}char *read(char *file_name, char *str) {FILE *file = fopen(file_name, "r");fgets(str, 200, file);fclose(file);return str;
}
char *merge(char *A, char *B, char *C) {int count = 0;for(int i = 0; A[i]; i++) {C[i] = A[i];count++;}for(int i = 0; B[i]; i++) {C[count] = B[i];count++;}C[count] = 0;return C;   
}void sort(char *str) {char *c = str;char *p = str + 1;char temp;while (*c){p = c + 1;while(*p) {if(*c > *p) {temp = *p;*p = *c;*c = temp;}p++;}c++;}
}
void write(char *file_name, char *str) {FILE *file = fopen(file_name, "w");fputs(str, file);fclose(file);
}

输出结果：

5. 将平均分写入文件中保存

参考第九章9_5题

代码：

#include "stdio.h"struct Student
{int num;char name[10];int score[3];int mean;
};
void print(struct Student *student, int count);
void input(struct Student *student, int count);
int get_mean(struct Student *student, int count);void main() {int count = 2;struct Student *student = (struct Student *) malloc (count * sizeof(struct Student));input(student, count);print(student, count);//printf("The mean score is: %d\n", get_mean(student, count));get_mean(student, count);FILE *file;file = fopen("stud", "w+");for(int i = 0; i < count; i++) {fwrite(&student[i], sizeof(struct Student), 1, file);}print(student, count);// for(int i = 0; i < count; i++) {//     fread(&student[i], sizeof(struct Student), 1, file);//     printf("The student info is %d, %s, %d, %d, %d, %d\n", student->num, student->name, student->score[0], student->score[1], student->score[2], student->mean);// }fclose(file);free(student);
}
void print(struct Student *student, int count) {for(int i = 0; i < count; i++) {printf("The student info is %d, %s, %d, %d, %d, %d\n", student->num, student->name, student->score[0], student->score[1], student->score[2], student->mean);student++;}
}
void input(struct Student *student, int count) {for(int i = 0; i < count; i++) {printf("Please input student info(like 001,jin,100):");scanf("%d %s %d %d %d", &(student + i)->num, (student + i)->name, (student + i)->score, (student + i)->score + 1, (student + i)->score + 2);//(student + i)->num=1; (student + i)->name="jin"; (student + i)->score=100;}
}
int get_mean(struct Student *student,int count) {for(int i = 0; i < count; i++) {//printf("get_mean:%d", student->score[0]);student->mean = (student->score[0] + student->score[1] + student->score[2])/3;student++;}return 0;
}

输出结果：

6. 平均成绩排序

代码：

struct Student *head_node = c;struct Student *node = c->next;while (head_node->next){while(node) {if(head_node->mean > node->mean) {swap(&head_node->mean, &node->mean);for(int i = 0; i < 3; i++) {swap(&(head_node->score[i]), &(node->score[i]));}swap(&head_node->num, &node->num);for(int i = 0; i < 10; i++) {swap_c(&(head_node->name[i]), &(node->name[i]));}}node = node->next;}head_node = head_node->next;node = head_node->next;}}
void swap(int *a, int *b) {int temp;temp = *b;*b = *a;*a = temp;
}void swap_c(char *a, char *b) {char temp;temp = *b;*b = *a;*a = temp;
}

输出结果：

11. 读写文件

代码：

#include "stdio.h"void main() {FILE *file;file = fopen("test.txt", "a");char str[3][200];for(int i = 0; i < 3; i++) {gets(str[i]);int j = 0;while(str[i][j]) {if(str[i][j] >= 'a' && str[i][j] <= 'z') str[i][j] = str[i][j] + 'A' - 'a';j++;}fputs(str[i], file);}fclose(file);file = fopen("test.txt", "r");char str1[600];fgets(str1, 600, file);printf("%s", str1);fclose(file);
}

输出结果：