我存储到列表然后尝试显示它，但是当我调用显示功能时，我收到此错误。我不确定问题是什么，因为它没有给我任何警告或错误。
typedef struct {
// Variables - Details on person taking survey
int ppsNo;
char firstName[15];
char lastName[15];
char address[30];
char email[30];
// Groups - Statistics are broken down based on these groups
int age;
int income;
int gender;
// Survey - What the survey questions will consist of
int exercise;
int alcohol;
int cigarettes;
}survey_t; // Structure defined
struct list_el{
survey_t data;
struct list_el* next;
}; // List for passing values into the struct
我接受值
void addSurvey(struct list_el** pointer) {
struct list_el* data;
data = (struct list_el*)malloc(sizeof(struct list_el));
printf("\n===== Adding Someone to the Survey =====\n");
// Depending on the number added, they output will be different
// Taking in details and passing through the list
printf("Enter PPS Number: ");
scanf("%d", &data->data.ppsNo);
printf("Enter First Name: ");
scanf("%s", data->data.firstName);
printf("Enter Last Name: ");
scanf("%s", data->data.lastName);
printf("Enter Address: ");
scanf("%s", data->data.address);
printf("Enter Email Address: ");
scanf("%s", data->data.email);
// Number added will determine the age group
printf("\nEnter age group\n");
printf("\t1: 18 - 20\n");
printf("\t2: 20 - 30\n");
printf("\t3: 30 - 50\n");
printf("\t4: 50 - 65\n");
printf("\t5: 65+\n");
scanf("%d", &data->data.age);
if (data->data.age > 5 && data->data.age < 1) {
printf("Error - Re Enter Age group\n");
scanf("%d", &data->data.age);
}
// Number added will determine income group
printf("\nIncome Bracket - What category do you fall under\n");
printf("\t1: No Income\n");
printf("\t2: Less than 20,000\n");
printf("\t3: Less than 40,000\n");
printf("\t4: Less than 60,000\n");
printf("\t5: Less than 80,000\n");
printf("\t6: Less than 100,000\n");
printf("\t7: Greater than 100,000\n");
scanf("%d", &data->data.income);
if (data->data.income > 7 && data->data.income < 1) {
printf("Error - Re Enter Income\n");
scanf("%d", &data->data.income);
}
// Number added will determine gender
printf("\nGender\n");
printf("\t1: Male\n");
printf("\t2: Female\n");
scanf("%d", &data->data.gender);
if (data->data.gender > 2 && data->data.gender < 1) {
printf("Error - Re Enter Gender\n");
scanf("%d", &data->data.gender);
}
// Number will be added to determine how often they exercise
printf("\nExercise - How often do you exercise\n");
printf("\t1: Never\n");
printf("\t2: Less than three times per week\n");
printf("\t3: Less than five times per week\n");
printf("\t4: More than five times per week\n");
scanf("%d", &data->data.exercise);
if (data->data.exercise > 4 && data->data.exercise < 1) {
printf("Error - Re Enter Exercise\n");
scanf("%d", &data->data.exercise);
}
// Number will be added to determine how many units they drink
printf("\nAlcohol - How many units of Alcohol do you drink per week\n");
printf("\t1: None\n");
printf("\t2: Less than 2 Units per week\n");
printf("\t3: Less than 3 Units per week\n");
printf("\t4: More than 4 Units per week\n");
scanf("%d", &data->data.alcohol);
if (data->data.alcohol > 4 && data->data.alcohol < 1) {
printf("Error - Re Enter Alcohol\n");
scanf("%d", &data->data.alcohol);
}
// Number will be added to determine how many cigarattes per week they smoke
printf("\nCigarettes - How many Cigarettes do you smoke per week\n");
printf("\t1: None\n");
printf("\t2: Less than 20 cigarettes per week\n");
printf("\t3: Less than 40 cigarettes per week\n");
printf("\t4: More than 40 cigarettes per week\n");
scanf("%d", &data->data.alcohol);
if (data->data.alcohol > 4 && data->data.alcohol < 1) {
printf("Error - Re Enter Alcohol\n");
scanf("%d", &data->data.alcohol);
}
}
要显示的功能
void displayAll(struct list_el *pointer) {
struct list_el *temp;
temp = pointer;
if (pointer == NULL) {
printf("Nothing to Display");
}
else {
while (temp != NULL) {
printf("\nDisplaying All Surveys\n");
printf("Name: %s %s", temp->data.firstName, temp->data.lastName);
printf("\nPPS: %d", temp->data.ppsNo);
printf("\nAddress: %s", temp->data.address);
printf("\nAddress: %s", temp->data.email);
// Switch statement that determines the age group depending on the value
switch (temp->data.age) {
case 1:
printf("\n18 - 20");
break;
case 2:
printf("\n20 - 30");
break;
case 3:
printf("\n30 - 50");
break;
case 4:
printf("\n50 - 65");
break;
case 5:
printf("\n65+");
break;
}
switch (temp->data.income) {
case 1:
printf("\nNo Income");
break;
case 2:
printf("\nLess than 20,000");
break;
case 3:
printf("\nLess than 40,000");
break;
case 4:
printf("\nLess than 60,000");
break;
case 5:
printf("\nLess than 80,000");
break;
case 6:
printf("\nLess than 100,000");
break;
case 7:
printf("\nGreater than 100,000");
break;
}
switch (temp->data.age) {
case 1:
printf("\nMale");
break;
case 2:
printf("\nFemale");
break;
}
switch (temp->data.exercise) {
case 1:
printf("\t1: Never\n");
break;
case 2:
printf("\nExercises less than three times per week");
break;
case 3:
printf("\nExercises less than five times per week");
break;
case 4:
printf("\n Exercises more than five times per week");
break;
}
switch (temp->data.alcohol) {
case 1:
printf("\nNo Units\n");
break;
case 2:
printf("\nLess than 2 Units per week");
break;
case 3:
printf("\nLess than 3 Units per week");
break;
case 4:
printf("\nMore than 4 Units per week");
break;
}
switch (temp->data.cigarettes) {
case 1:
printf("\nNo Cigarettes");
break;
case 2:
printf("\nLess than 20 cigarettes per week");
break;
case 3:
printf("\nLess than 40 cigarettes per week");
break;
case 4:
printf("\nMore than 40 cigarettes per week");
break;
}
temp = temp->next;
}
}
}
如果有人能够解释错误的含义，我将非常感谢，以备将来使用，所以我知道将来如何处理它。
答案 0 :(得分：1)
未初始化的指针。在调试模式下，堆栈通常填充0xCC值，以便更快地检测错误。
答案 1 :(得分：0)
错误表示您正在尝试访问（读/写）非法地址的内存。通常，这意味着您取消引用非法指针值。
您的列表似乎不完整。
在此代码中：
void addSurvey(struct list_el** pointer) {
struct list_el* data;
data = (struct list_el*)malloc(sizeof(struct list_el));
...
似乎你永远不会使用pointer。换句话说，您似乎没有将新元素添加到列表中。你错过了什么：
*pointer = data;
此外，您应该初始化新元素的next，即
data->next = NULL;