在此计划中：
#include <stdio.h>
#include <stdlib.h> /* for malloc */
#include <ctype.h>
#define STD_WORK_WEEK 40
#define OVERTIME_RATE 1.5
struct employee
{
char first_name[10];
char last_name[10];
long id_number;
float wage;
float hours;
float overtime;
float gross;
struct employee *next;
};
/************************************************************************/
/* Function: Gross_pay_calc */
/* */
/* Purpose: Calculates gross pay of an employee using hours and */
/* wage data that is already stored */
/* */
/* */
/* Parameters: wage - Array of employee wages */
/* hours- Array of number of hours worked by an employee */
/* grossPay- Gross Pay of an employee */
/* size-number of employees to process */
/* */
/* Returns: Stores grossPay to be referenced in another function output */
/* */
/************************************************************************/
/* Function call to calculate gross pay. */
void Gross_pay_calc (struct employee *emp1)
{
/*Local Variable Declaration */
struct employee *tmp; /* tmp pointer value to current node */
if ( tmp->hours <= STD_WORK_WEEK ) /* Calculates grossPay based on <40 or >40 for OT */
{
tmp->gross = tmp->wage*tmp->hours;
}
else
{
tmp->gross = (tmp->wage*STD_WORK_WEEK)+((tmp->hours-STD_WORK_WEEK)* (tmp->wage*OVERTIME_RATE));
}
}
/*-----------------------------------------------------------------------------*/
/* */
/* FUNCTION: print_list */
/* */
/* DESCRIPTION: This function will print the contents of a linked */
/* list. It will traverse the list from beginning to the */
/* end, printing the contents at each node. */
/* */
/* PARAMETERS: emp1 - pointer to a linked list */
/* */
/* OUTPUTS: None */
/* */
/* CALLS: None */
/* */
/*-----------------------------------------------------------------------------*/
void print_list(struct employee *emp1)
{
struct employee *tmp; /* tmp pointer value to current node */
int i = 0; /* counts the nodes printed */
printf ("--------------------------------------------------------------\n"); /*Print Header To Screen */
printf (" Name \t Clock# \t Wage \t Hours \t OT \t Gross\n");
printf ("---------------------------------------------------------------\n");
/* Start a beginning of list and print out each value */
/* loop until tmp points to null (remember null is 0 or false) */
for(tmp = emp1; tmp ; tmp = tmp->next)
{
i++;
/* TODO - print other members as well */
printf("\n %s %s %6d %8.2f %5.2f %7.2f\n",tmp->first_name,tmp->last_name,tmp->id_number,
tmp->wage,tmp->hours,tmp->gross);
}
printf("\n\nTotal Number of Employees = %d\n", i);
}
/*----------------------------------------------------------------------------*/
/* */
/* FUNCTION: main */
/* */
/* DESCRIPTION: This function will prompt the user for an employee */
/* id and wage until the user indicates they are finished. */
/* At that point, a list of id and wages will be */
/* generated. */
/* */
/* PARAMETERS: None */
/* */
/* OUTPUTS: None */
/* */
/* CALLS: print_list */
/* */
/*----------------------------------------------------------------------------*/
int main ()
{
char answer[80]; /* to see if the user wants to add more employees */
int more_data = 1; /* flag to check if another employee is to be processed */
char value; /* gets the first character of answer */
struct employee *current_ptr, /* pointer to current node */
*head_ptr; /* always points to first node */
/* Set up storage for first node */
head_ptr = (struct employee *) malloc (sizeof(struct employee));
current_ptr = head_ptr;
while (more_data)
{
/* Read in Employee ID and Hourly Wage */
printf("\nEnter employee ID: ");
scanf("%li", & current_ptr -> id_number);
printf("\nEnter employee weekly wage: ");
scanf("%f", & current_ptr -> wage);
printf("\nEnter employee weekly hours: ");
scanf("%f", & current_ptr -> hours);
printf("\nEnter First Name: ");
scanf("%s", & current_ptr -> first_name);
printf("\nEnter Last Name: ");
scanf("%s", & current_ptr -> last_name);
printf("Would you like to add another employee? (y/n): ");
scanf("%s", answer);
Gross_pay_calc(head_ptr);
/* Ask user if they want to add another employee */
if ((value = toupper(answer[0])) != 'Y')
{
current_ptr->next = (struct employee *) NULL;
more_data = 0;
}
else
{
/* set the next pointer of the current node to point to the new node */
current_ptr->next = (struct employee *) malloc (sizeof(struct employee));
/* move the current node pointer to the new node */
current_ptr = current_ptr->next;
}
} /* while */
/* print out listing of all employee id's and wages that were entered */
print_list(head_ptr);
printf("\n\nEnd of program\n");
return 0;
}
我正在尝试使用gross_pay_calc来计算我在请求中输入的每位员工的总薪酬。但是，当我尝试在print_list函数中打印tmp-＆gt;总值时，它无法正确计算。我不确定为什么会这样，并且会喜欢有关如何准确计算的任何建议！
答案 0 :(得分：3)
两件事，第一，你的直接问题。正如在注释中所提到的，在Gross_pay_calc中，您通过不确定的指针tmp访问内存。它在被取消引用之前从未设置为有效内存，因此它是未定义的行为。请尝试使用传入的参数emp1：
/* Function call to calculate gross pay. */
void Gross_pay_calc (struct employee *emp1)
{
if ( emp1->hours <= STD_WORK_WEEK ) /* Calculates grossPay based on <40 or >40 for OT */
{
emp1->gross = emp1->wage*emp1->hours;
}
else
{
emp1->gross = (emp1->wage*STD_WORK_WEEK) +
((emp1->hours-STD_WORK_WEEK) * (emp1->wage*OVERTIME_RATE));
}
}
其次，填充链表的算法过度工作。一个简单的指针指针可以使循环更多更简洁：
int main ()
{
char answer[80]; /* to see if the user wants to add more employees */
struct employee *head_ptr = NULL; /* the list head pointer */
struct employee **next_ptr = &head_ptr; /*always holds the address of the next pointer to fill */
do
{ /* allocate new node wherever *next_ptr says to. initially it will be
the head pointer. after that, the next-ptr of the last node added. */
*next_ptr = calloc(1, sizeof(**next_ptr));
/* Read in Employee ID and Hourly Wage */
printf("\nEnter employee ID: ");
scanf("%li", &(*next_ptr)->id_number);
printf("\nEnter employee weekly wage: ");
scanf("%f", &(*next_ptr)->wage);
printf("\nEnter employee weekly hours: ");
scanf("%f", &(*next_ptr)->hours);
printf("\nEnter First Name: ");
scanf("%s", (*next_ptr)->first_name);
printf("\nEnter Last Name: ");
scanf("%s", (*next_ptr)->last_name);
Gross_pay_calc(*next_ptr);
// move to the next pointer we'll be filling
next_ptr = &(*next_ptr)->next;
/* Ask user if they want to add another employee */
printf("Would you like to add another employee? (y/n): ");
scanf("%s", answer);
if (toupper(answer[0]) != 'Y')
break;
} while (1);
// always set the last pointer to nothing.
*next_ptr = NULL;
/* print out listing of all employee id's and wages that were entered */
print_list(head_ptr);
printf("\n\nEnd of program\n");
return 0;
}
同样，打印设备也可以清理一下：
void print_list(struct employee *emp1)
{
int i = 0; /* counts the nodes printed */
printf ("--------------------------------------------------------------\n");
printf (" Name \t Clock# \t Wage \t Hours \t OT \t Gross\n");
printf ("---------------------------------------------------------------\n");
/* Start a beginning of list and print out each value */
/* loop until tmp points to null (remember null is 0 or false) */
for (;emp1; ++i, emp1 = emp1->next)
{
printf("\n %s %s %6ld %8.2f %5.2f %7.2f\n",
emp1->first_name,emp1->last_name,emp1->id_number,
emp1->wage,emp1->hours,emp1->gross);
}
printf("\n\nTotal Number of Employees = %d\n", i);
}