根据我的理解，有一种解析输入的方法：
一百万美元退出$$$ 16岁的Cheit及其惩罚$$$ 8战争和纪念$$$ 12
战争之风$$$ 12如何玩足球$$$ 12
超短 脉冲$$$ 8
非线性光学$$$ 8
等..
“$$$”在数据字段之间分开 我正在寻求升级这句话：
sscanf(line, " %200[^$][^$][^$]$$$%ld", name, &copies);
所以它适合行号。示例中的1。
修改
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define NAME_LENGTH 200
#define ERROR -1
typedef int BOOL;
#define TRUE 1
#define FALSE 0
typedef struct book{
char name[NAME_LENGTH];
long copies;
struct book *next;
} Book;
Book* create_book(char name[], long copies){
Book *new_book = (Book*) malloc(sizeof(Book));
if (new_book != NULL) {
strcpy(new_book->name, name);
new_book->next = NULL;
new_book->copies = copies;
}
return new_book;
}
Book* add_first(Book *head, char name[], long copies){
Book *new_book = create_book(name, copies);
if (new_book == NULL)
return NULL;
new_book->next = head;
return new_book;
}
Book* add_last(Book *head, char name[], long copies){
Book *tail;
Book *new_book = create_book(name, copies);
if (new_book == NULL)
return NULL;
if (head == NULL)
return new_book;
tail = head;
while (tail->next != NULL)
tail = tail->next;
tail->next = new_book;
return head;
}
Book* add_sorted(Book *head, char name[], long copies){
Book* iter, *prev = NULL;
Book* new_book = create_book(name, copies);
if(new_book == NULL)
return head;
if (head == NULL)
return new_book;
if (!strcmp(new_book->name, head->name)){
new_book->next = head;
return new_book;
}
iter = head;
while ((iter != NULL) && (strcmp(new_book->name, head->name))){
prev = iter;
iter = iter->next;
}
prev->next = new_book;
new_book->next = iter;
return head;
}
int length(const Book *head){
if (head == NULL)
return 0;
return 1 + length(head->next);
}
void free_library(Book *head_book){
if (head_book == NULL)
return;
free_library(head_book->next);
free(head_book);
}
Book* find_book(Book *head, char name[]){
if (head == NULL)
return NULL;
if (strcmp(head->name, name) == 0)
return head;
find_book(head->next, name);
return NULL;
}
Book* delete_book(Book *head, char name[]){
Book *iter = head, *prev = NULL;
if (head == NULL)
return head;
if ((!strcmp(head->name, name)) == 1){
iter = head->next;
free(head);
return iter;
}
while (iter->next != NULL){
if ((!strcmp(head->name, name)) == 1){
prev->next = iter->next;
free(iter);
break;
}
prev = iter;
iter = iter->next;
}
return head;
}
Book* initBooksList(FILE *input){
Book *head_book = NULL, *existing_book = NULL;
long copies = 0;
char line[256] = {0}, name[NAME_LENGTH];
if (input == NULL){
printf("File did not open. Exit..\n");
return NULL;
}
while(!feof(input)){
if((fgets(line, 256, input) != NULL) && (head_book == NULL)){
sscanf(line, " %200[^$][^$][^$]$$$%ld", name, &copies);
printf("%s\n%ld\n", name, copies);
head_book = create_book(name, copies);
strcpy(line, "");
strcpy(name, "");
copies = 0;
}
else{
sscanf(line, " %200[^$][^$][^$]$$$%ld", name, &copies);
existing_book = find_book(head_book, name);
if(existing_book != NULL){
existing_book->copies += copies;
printf("%s\n%ld\n", name, existing_book->copies);
}
else{
add_sorted(head_book, name, copies);
printf("%s\n%ld\n", name, copies);
strcpy(line, "");
strcpy(name, "");
copies = 0;
}
}
}
return head_book;
}
void storeBooks(Book *head_book){
}
void returnBook(Book *head_book){
}
void borrowBook(Book *head_book){
}
int main(int argc, char *argv[]){
int i = 0;
FILE *ptr;
printf("%d\n", argc);
for(i = 0; i < argc; i++)
printf("argv[%d] = %s\n", i, argv[i]);
ptr = fopen(argv[1], "r");
initBooksList(ptr);
return 0;
}
答案 0 :(得分：0)
这应该让你知道你可以做什么：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
char line[] = "The Cheit and its Punishment $$$ 8";
char *seppointer = strchr(line, '$');
*seppointer = 0;
int price = atoi(seppointer + 4);
printf("Title: %s\nPrice: %d\n", line, price);
}
免责声明：没有错误检查，并且假设该行具有所需的格式。
答案 1 :(得分：0)
如果你知道最长的标题是200个字符，如your comment所示，你可以为此分配一个数组（包括空终止符的空格）。
您可以使用fscanf()使用格式字符串" %200[^$]$$$%d"来解析文件的行。第一个空格告诉fscanf()跳过前导空格，这些空格可能会从之前的I / O操作中遗留下来。下一个转换说明符是%200[^$]，它告诉fscanf()将任何字符读入字符串，直到遇到$为止。 $保留在输入流中。请注意，此处指定的最大宽度为200，以防止缓冲区溢出。格式字符串中的后三个字符$$$必须存在于输入中，并且在到达最终转换说明符%d之前匹配。
#include <stdio.h>
#include <stdlib.h>
#define MAX_TITLE 201
int main(void)
{
/* Open file, and check for success */
FILE *fp = fopen("data.txt", "r");
if (fp == NULL) {
perror("Unable to open file");
exit(EXIT_FAILURE);
}
char title[MAX_TITLE];
int price;
while (fscanf(fp, " %200[^$]$$$%d", title, &price) == 2) {
printf("Title: %s --- Price: $%d\n", title, price);
}
fclose(fp);
return 0;
}
以下是针对输入文件运行时的程序输出：
Title: The Cheit and its Punishment --- Price: $8
Title: War and Remembrance --- Price: $12
Title: Winds of War --- Price: $12
Title: How to Play Football --- Price: $12
Title: Ultrashort Pulses --- Price: $8
Title: Nonlinear Optics --- Price: $8
上述代码中对fscanf()的调用会在输入流中每行的最后一个数字后面留下空白字符;这就是为什么需要格式字符串中的前导空格的原因。更好的解决方案是使用fgets()来获取输入行，使用sscanf()来解析行。应该分配buffer来保存每行的内容;这里的慷慨分配是好的，因为它减少了长输入在输入流中留下字符的可能性。如果输入可能较长，则应在下次调用fgets()之前添加代码以清除输入流。
这种方法的一个优点是，由于读取的整行包括\n，因此不需要像以前一样跳过前导空白字符。另一个优点是最终数字之后的虚假字符可以被忽略，或者由代码处理;由于存储了该线，因此可以根据需要多次检查和扫描。最终编号后面的字符会导致第一个版本出现问题，第一个版本只能跳过前导空格。
#include <stdio.h>
#include <stdlib.h>
#define BUF_SZ 1000
#define MAX_TITLE 201
int main(void)
{
/* Open file, and check for success */
FILE *fp = fopen("data.txt", "r");
if (fp == NULL) {
perror("Unable to open file");
exit(EXIT_FAILURE);
}
char buffer[BUF_SZ];
char title[MAX_TITLE];
int price;
size_t lnum = 0;
while (fgets(buffer, BUF_SZ, fp) != NULL) {
++lnum;
if (sscanf(buffer, "%200[^$]$$$%d", title, &price) == 2) {
printf("Title: %s --- Price: $%d\n", title, price);
} else {
fprintf(stderr, "Format error in line %zu\n", lnum);
}
}
fclose(fp);
return 0;
}
此处使用fgets()可以更灵活地检查输入。要处理$是标题的一部分的情况，您可以使用strstr()首先找到分隔符" $$$"，然后将字符复制到分隔符到title[]数组中在一个循环中。由于strstr()返回指向找到的字符串的指针，因此可以将此指针指定给sscanf()以选择最终的数字。如果找不到该字符串，strstr()函数将返回空指针，这可用于标识具有格式问题的行。请注意strstr()位于string.h：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define BUF_SZ 1000
#define MAX_TITLE 201
int main(void)
{
/* Open file, and check for success */
FILE *fp = fopen("data.txt", "r");
if (fp == NULL) {
perror("Unable to open file");
exit(EXIT_FAILURE);
}
char buffer[BUF_SZ];
char title[MAX_TITLE];
int copies;
size_t lnum = 0;
while (fgets(buffer, BUF_SZ, fp) != NULL) {
++lnum;
/* Find delimiter string in buffer */
char *title_end = strstr(buffer, " $$$");
if (title_end == NULL) {
fprintf(stderr, "Format error in line %zu\n", lnum);
continue;
} else {
/* Copy characters into title until space before delimiter */
char *curr = buffer;
size_t i = 0;
while (curr < title_end && i < MAX_TITLE) {
title[i] = buffer[i];
++curr;
++i;
}
title[i] = '\0';
}
if (sscanf(title_end, " $$$%d", &copies) == 1) {
printf("Title: %s --- Copies: %d\n", title, copies);
} else {
fprintf(stderr, "Format error in line %zu\n", lnum);
}
}
fclose(fp);
return 0;
}
以下是修改后的输入文件：
The Cheit and its Punishment $$$ 8
War and Remembrance $$$ 12
Winds of War $$$ 12
A million $ exit $$$ 16
How to Play Football $$$ 12
Ultrashort Pulses $$$ 8
Nonlinear Optics $$$ 8
以及结果输出：
Title: The Cheit and its Punishment --- Copies: 8
Title: War and Remembrance --- Copies: 12
Title: Winds of War --- Copies: 12
Title: A million $ exit --- Copies: 16
Title: How to Play Football --- Copies: 12
Title: Ultrashort Pulses --- Copies: 8
Title: Nonlinear Optics --- Copies: 8