我正在参加测试，并有一个问题：修改该程序，使其采用不同格式的输入：每行包含年龄，逗号，空格和名称，例如
23, Angus McGurkinshaw
我了解我需要在readOneStudent函数中进行一些修改。不确定如何通过知道逗号的地址来读取名称。请帮忙。 输入和输出应如下所示：
input = 21, Fred Nurk
927, Arwen Evensong
output is suppose to be:
Arwen Evensong (927)
Fred Nurk (21)
..
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MAX_LINE_LENGTH 80 // The longest line this program will accept
#define MAX_NUM_STUDENTS 500 // The maximum number of students this program can handle
#define MAX_NAME_SIZE 50 // The maximum allowable name length
typedef struct student_s Student;
struct student_s {
char name[MAX_NAME_SIZE];
int age;
Student* next; // Pointer to next student in a list
};
// Create a pool of student records to be allocated on demand
Student studentPool[MAX_NUM_STUDENTS]; // The student pool
int firstFree = 0;
// Return a pointer to a new student record from the pool, after
// filling in the provided name and age fields. Returns NULL if
// the student pool is exhausted.
Student* newStudent(const char* name, int age)
{
Student* student = NULL;
if (firstFree < MAX_NUM_STUDENTS) {
student = &studentPool[firstFree];
firstFree += 1;
strncpy(student->name, name, MAX_NAME_SIZE);
student->name[MAX_NAME_SIZE - 1] = '\0'; // Make sure it's terminated
student->age = age;
student->next = NULL;
}
return student;
}
// Read a single student from a csv input file with student name in first column,
// and student age in second.
// Returns: A pointer to a Student record, or NULL if EOF or an invalid
// student record is read. Blank lines, or lines in which the name is
// longer than the provided name buffer, or there is no comma in the line
// are considered invalid.
Student* readOneStudent(FILE* file)
{
char buffer[MAX_LINE_LENGTH]; // Buffer into which we read a line from stdin
Student* student = NULL; // Pointer to a student record from the pool
// Read a line, extract name and age
char* inputLine = fgets(buffer, MAX_LINE_LENGTH, file);
if (inputLine != NULL) { // Proceed only if we read something
char* commaPos = strchr(buffer, ',');
if (commaPos != NULL) {
int age = atoi(commaPos + 1);
*commaPos = '\0'; // null-terminate the name
student = newStudent(buffer, age);
}
}
return student;
}
Student* readStudents(FILE *file)
{
Student* first = NULL; // Pointer to the first student in the list
Student* last = NULL; // Pointer to the last student in the list
Student* student = readOneStudent(file);
while (student != NULL) {
if (first == NULL) {
first = last = student; // Empty list case
} else {
student -> next = first;
first = student;
}
student = readOneStudent(file);
}
return first;
}
// printOneStudent: prints a single student, passed by value
void printOneStudent(Student student)
{
printf("%s (%d)\n", student.name, student.age);
}
// printStudents: print all students in a list of students, passed
// by reference
void printStudents(const Student* student)
{
while (student != NULL) {
printOneStudent(*student);
student = student->next;
}
}
int main(void)
{
FILE* inputFile = stdin;
if (inputFile == NULL) {
fprintf(stderr, "File not found\n");
} else {
Student* studentList = readStudents(inputFile);
printStudents(studentList);
}
}
答案 0 :(得分：1)
下面的代码应该可以工作。 请注意
strchr()
This returns a pointer to the first occurrence of the character c in the string str, or NULL if the character is not found.
我认为您正在尝试从名称字符串中获取年龄。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MAX_LINE_LENGTH 80 // The longest line this program will accept
#define MAX_NUM_STUDENTS 500 // The maximum number of students this program can handle
#define MAX_NAME_SIZE 50 // The maximum allowable name length
typedef struct student_s Student;
struct student_s {
char name[MAX_NAME_SIZE];
int age;
Student* next; // Pointer to next student in a list
};
// Create a pool of student records to be allocated on demand
Student studentPool[MAX_NUM_STUDENTS]; // The student pool
int firstFree = 0;
// Return a pointer to a new student record from the pool, after
// filling in the provided name and age fields. Returns NULL if
// the student pool is exhausted.
Student* newStudent(const char* name, int age)
{
Student* student = NULL;
if (firstFree < MAX_NUM_STUDENTS) {
student = &studentPool[firstFree];
firstFree += 1;
strncpy(student->name, name, MAX_NAME_SIZE);
student->name[MAX_NAME_SIZE - 1] = '\0'; // Make sure it's terminated
student->age = age;
student->next = NULL;
}
return student;
}
// Read a single student from a csv input file with student name in first column,
// and student age in second.
// Returns: A pointer to a Student record, or NULL if EOF or an invalid
// student record is read. Blank lines, or lines in which the name is
// longer than the provided name buffer, or there is no comma in the line
// are considered invalid.
Student* readOneStudent(FILE* file)
{
char buffer[MAX_LINE_LENGTH]; // Buffer into which we read a line from stdin
Student* student = NULL; // Pointer to a student record from the pool
// Read a line, extract name and age
char* inputLine = fgets(buffer, MAX_LINE_LENGTH, file);
if (inputLine != NULL) { // Proceed only if we read something
char* commaPos = strchr(buffer, ',');
if (commaPos != NULL) {
// int age = atoi(commaPos + 1);
//printf("age and commaPos is %d,%s \n ",age,commaPos);
char* name = commaPos+1;
name[strcspn(name, "\n")] = 0; //remove /n from fgets
*commaPos = '\0'; // null-terminate the age
int age = atoi(buffer);
//printf("age and commaPos is %d,%s \n ",age,name);
//student = newStudent(buffer, age);
student = newStudent(name, age);
}
}
return student;
}
Student* readStudents(FILE *file)
{
Student* first = NULL; // Pointer to the first student in the list
Student* last = NULL; // Pointer to the last student in the list
Student* student = readOneStudent(file);
while (student != NULL) {
if (first == NULL) {
first = last = student; // Empty list case
} else {
student -> next = first;
first = student;
}
student = readOneStudent(file);
}
return first;
}
// printOneStudent: prints a single student, passed by value
void printOneStudent(Student student)
{
printf("%s (%d)\n", student.name, student.age);
}
// printStudents: print all students in a list of students, passed
// by reference
void printStudents(const Student* student)
{
while (student != NULL) {
printOneStudent(*student);
student = student->next;
}
}
int main(void)
{
FILE* inputFile = stdin;
if (inputFile == NULL) {
fprintf(stderr, "File not found\n");
} else {
Student* studentList = readStudents(inputFile);
printStudents(studentList);
}
}