练习13-1
#include <stdio.h>int main(void){FILE *fp;char file_name[128];printf("file name:");scanf("%s",file_name);fp = fopen(file_name, "r");//相对路径是跟源代码一样的路径if (fp == NULL)printf("\a无法打开文件\"%s\"。\n",file_name);else {printf("\a成功打开了文件\"%s\"。\n",file_name);fclose(fp);}return 0;}
练习13-2
#include <stdio.h>int main(void){FILE *fp;char file_name[128];printf("file name:");scanf("%s",file_name);fp = fopen(file_name, "w");//相对路径是跟源代码一样的路径if (fp == NULL)printf("\a无法打开文件\"%s\"。\n",file_name);else {printf("\a成功打开了文件\"%s\"。\n",file_name);fclose(fp);}return 0;}
练习13-3
#include <stdio.h>#define NUM 6typedef struct {char name[100];double height;double weight;}Student;void swap_Student(Student *x, Student *y){Student temp = *x;*x = *y;*y = temp;}void sort_by_height(Student a[], int n){int i, j;for (i = 0; i < n - 1; i++) {for (j = n - 1; j > i; j--)if (a[j - 1].height > a[j].height){swap_Student(&a[j - 1], &a[j]);}}}int main(void){FILE *fp;int ninzu = 0;double hsum = 0.0;double wsum = 0.0;Student std[NUM];if ((fp = fopen("hw.dat", "r")) == NULL)printf("\a文件打开失败。\n");else {while (fscanf(fp, "%s%lf%lf", std[ninzu].name, &(std[ninzu].height), &(std[ninzu].weight)) == 3) {hsum += std[ninzu].height;wsum += std[ninzu].weight;ninzu++;}sort_by_height(std, NUM);for (ninzu = 0; ninzu<NUM; ninzu++)printf("%-10s %5.1f %5.1f\n", std[ninzu].name, std[ninzu].height, std[ninzu].weight);printf("----------------------\n");printf("平均 %5.1f %5.1f\n", hsum / ninzu, wsum / ninzu);fclose(fp);}return 0;}
练习13-4
#include <stdio.h>int main(void){FILE *fp;char name[100];double height, weight;fp = fopen("read_from_keyboard.txt","w");//file created in the same path as source code pathputs("input name(char[]) height(double) weight(double)");puts("input invalid value to end input");while (scanf("%s%lf%lf", name, &height, &weight) == 3) {fprintf(fp,"%-10s %5.1f %5.1f\n", name, height, weight);}fclose(fp);printf("done!");return 0;}
练习13-5
#include <time.h>#include <stdio.h>char data_file[] = "datetime.dat";char kimochi[128];void get_data(void){FILE *fp;if ((fp = fopen(data_file, "r")) == NULL){printf("本程序第一次运行。\n");printf("当前的心情：");scanf("%s",kimochi);}else {int year, month, day, h, m, s;fscanf(fp, "%d%d%d%d%d%d", &year, &month, &day, &h, &m, &s);printf("上一次运行是在%d年%d月%d日%d时%d分%d秒。\n",year, month, day, h, m, s);fscanf(fp, "%s", kimochi);printf("上一次心情:%s",kimochi);printf("当前的心情:");scanf("%s", kimochi);fclose(fp);}}void put_data(void){FILE *fp;time_t current = time(NULL);/* 当前日历时间 */struct tm *timer = localtime(¤t);/* 分解时间*/if ((fp = fopen(data_file, "w")) == NULL)printf("\a文件打开失败。\n");else {fprintf(fp, "%d %d %d %d %d %d\n",timer->tm_year + 1900, timer->tm_mon + 1, timer->tm_mday,timer->tm_hour, timer->tm_min, timer->tm_sec);fprintf(fp,"%s",kimochi);fclose(fp);}}int main(void){get_data();/* 取得并显示上一次运行时的日期和时间 */put_data();/* 写入本次运行时的日期和时间 */return 0;}
练习13-6
#include <stdio.h>char file_name[128];int main(void){int ch;int line_num = 0;FILE *fp;printf("input filename:");scanf("%s",file_name);if ((fp = fopen(file_name, "r")) == NULL){printf("文件打开失败。\n");}else{while ((ch = fgetc(fp)) != EOF){if (ch == '\n')line_num++;}printf("file has line number:%d",line_num);}return 0;}
练习13-7
#include <stdio.h>char file_name[128];int main(void){int ch;int ch_num = 0;FILE *fp;printf("input filename:");scanf("%s",file_name);if ((fp = fopen(file_name, "r")) == NULL){printf("文件打开失败。\n");}else{while ((ch = fgetc(fp)) != EOF){if(ch!='\n')ch_num++;}printf("file has character number:%d",ch_num);}return 0;}
练习13-8
#include <stdio.h>int main(void){int ch;FILE *sfp;/* 原文件 */FILE *dfp;/* 目标文件 */char sname[FILENAME_MAX];/* 原文件名 */char dname[FILENAME_MAX];/* 目标文件名 */printf("打开原文件："); scanf("%s", sname);printf("打开目标文件："); scanf("%s", dname);if ((sfp = fopen(sname, "r")) == NULL)printf("\a原文件打开失败。\n");else {if ((dfp = fopen(dname, "w")) == NULL)printf("\a目标文件打开失败。\n");else {while ((ch = fgetc(sfp)) != EOF){fputc(ch, dfp);//输出到目标文件printf("%c",ch);}fclose(dfp);}fclose(sfp);}return 0;}
练习13-9
#include <stdio.h>int main(void){int ch;FILE *sfp;/* 原文件 */FILE *dfp;/* 目标文件 */char sname[FILENAME_MAX];/* 原文件名 */char dname[FILENAME_MAX];/* 目标文件名 */printf("打开原文件："); scanf("%s", sname);printf("打开目标文件："); scanf("%s", dname);if ((sfp = fopen(sname, "r")) == NULL)printf("\a原文件打开失败。\n");else {if ((dfp = fopen(dname, "w")) == NULL)printf("\a目标文件打开失败。\n");else {while ((ch = fgetc(sfp)) != EOF){if ((ch >= 'a') && (ch <= 'z'))ch -= 32;fputc(ch, dfp);//输出到目标文件printf("%c",ch);}fclose(dfp);}fclose(sfp);}return 0;}
练习13-10
#include <stdio.h>int main(void){int ch;FILE *sfp;/* 原文件 */FILE *dfp;/* 目标文件 */char sname[FILENAME_MAX];/* 原文件名 */char dname[FILENAME_MAX];/* 目标文件名 */printf("打开原文件："); scanf("%s", sname);printf("打开目标文件："); scanf("%s", dname);if ((sfp = fopen(sname, "r")) == NULL)printf("\a原文件打开失败。\n");else {if ((dfp = fopen(dname, "w")) == NULL)printf("\a目标文件打开失败。\n");else {while ((ch = fgetc(sfp)) != EOF){if ((ch >= 'A') && (ch <= 'Z'))ch += 32;fputc(ch, dfp);//输出到目标文件printf("%c",ch);}fclose(dfp);}fclose(sfp);}return 0;}
练习13-11
#include <stdio.h>int main(void){FILE *fp;double haha[10] = {1.1,2.2,3.3,4.4,5.5,6.6,7.7,8.8,9.9,10.10};int i;for(i=0;i<10;i++){printf("从数组haha得到的元素haha[%d]为%23.21f。\n", i,haha[i]);}return 0;}
练习13-12
#include <time.h>#include <stdio.h>char data_file[] = "datetime.dat";void get_data(void){FILE *fp;if ((fp = fopen(data_file, "r")) == NULL)printf("本程序第一次运行。\n");else {int year, month, day, h, m, s;fscanf(fp, "%d%d%d%d%d%d", &year, &month, &day, &h, &m, &s);printf("上一次运行是在%d年%d月%d日%d时%d分%d秒。\n",year, month, day, h, m, s);fclose(fp);}}/*--- 写入本次运行时的日期和时间 ---*/void put_data(void){FILE *fp;time_t current = time(NULL);/* 当前日历时间 */struct tm *timer = localtime(¤t);/* 分解时间*/if ((fp = fopen(data_file, "w")) == NULL)/* 打开文件 */{printf("\a文件打开失败。\n");}else {fwrite(&timer, sizeof(struct tm), 1, fp);//以二进制格式写入fclose(fp);}}int main(void){get_data();/* 取得并显示上一次运行时的日期和时间 */put_data();/* 写入本次运行时的日期和时间 */return 0;}
练习13-13
#include <stdio.h>int main(void){int n;int ch;FILE *sfp;/* 原文件 */FILE *dfp;/* 目标文件 */char sname[FILENAME_MAX];/* 原文件名 */char dname[FILENAME_MAX];/* 目标文件名 */printf("打开原文件："); scanf("%s", sname);printf("打开目标文件："); scanf("%s", dname);if ((sfp = fopen(sname, "rb")) == NULL)printf("\a原文件打开失败。\n");else {if ((dfp = fopen(dname, "wb")) == NULL)printf("\a目标文件打开失败。\n");else {while (n = fread(&ch, sizeof(int), 1, sfp) > 0){fwrite(&ch, sizeof(int), 1, dfp);}fclose(dfp);}fclose(sfp);printf("done!\n");}return 0;}
hw.dat
Aiba 160 59.3Kurata 162 51.6Masaki 182 76.5Tanaka 170 60.7Tsuji 175 83.9Washio 175 72.5
