我正在尝试使用 Makefile 编译 5 个 *.c 文件(gcc -o prog add.c create.c delete.c display.c main .c) 但我收到了 variable is not declared 错误。我在上面的命令中创建了将 main.c 放在第一位，但仍然出现相同的错误。
有人可以指出我在这里做错了什么，我怎样才能创建变量以便编译器可以读取它？
同样下面的代码被分成了5个文件 错误:
add.c: In function ‘add’:
add.c:3:2: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
printf("\n\n\t\t\t\t*****ADD Menu*****");
^~~~~~
add.c:3:2: warning: incompatible implicit declaration of built-in function ‘printf’
add.c:3:2: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
add.c:5:6: error: ‘left’ undeclared (first use in this function)
if (left == SIZE - 1)
^~~~
add.c:5:6: note: each undeclared identifier is reported only once for each function it appears in
add.c:5:14: error: ‘SIZE’ undeclared (first use in this function)
if (left == SIZE - 1)
^~~~
add.c:12:3: warning: implicit declaration of function ‘scanf_s’ [-Wimplicit-function-declaration]
scanf_s("%d", &holder);
^~~~~~~
add.c:15:3: error: ‘numarr’ undeclared (first use in this function)
numarr[left] = holder;
^~~~~~
add.c:16:7: error: ‘right’ undeclared (first use in this function)
if (right == -1)
^~~~~
create.c: In function ‘create’:
create.c:3:2: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
printf("\n\n\t\t\t\tArray has been created with the size of 10 elements");
^~~~~~
create.c:3:2: warning: incompatible implicit declaration of built-in function ‘printf’
create.c:3:2: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
delete.c: In function ‘delete’:
delete.c:4:6: error: ‘right’ undeclared (first use in this function)
if (right == -1)
^~~~~
delete.c:4:6: note: each undeclared identifier is reported only once for each function it appears in
delete.c:6:3: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
printf("\n\n\t\t\t\tERROR! Queue is empty. Please add element before deleting them");
^~~~~~
delete.c:6:3: warning: incompatible implicit declaration of built-in function ‘printf’
delete.c:6:3: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
delete.c:10:12: error: ‘numarr’ undeclared (first use in this function)
holder = numarr[right];
^~~~~~
delete.c:11:3: warning: incompatible implicit declaration of built-in function ‘printf’
printf("\n\n\t\t\t\tSUCCESS. Deleted item: %d", holder);
^~~~~~
delete.c:11:3: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
delete.c:13:15: error: ‘left’ undeclared (first use in this function)
if (right == left)
^~~~
display.c: In function ‘display’:
display.c:4:6: error: ‘right’ undeclared (first use in this function)
if (right == -1)
^~~~~
display.c:4:6: note: each undeclared identifier is reported only once for each function it appears in
display.c:6:3: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
printf("\n\n\t\t\t\tEmter elements to array to be displayed here!");
^~~~~~
display.c:6:3: warning: incompatible implicit declaration of built-in function ‘printf’
display.c:6:3: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
display.c:10:3: warning: incompatible implicit declaration of built-in function ‘printf’
printf("\n\n\t\t\t\tDisplay of current elements in queue: ");
^~~~~~
display.c:10:3: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
display.c:11:24: error: ‘left’ undeclared (first use in this function)
for (i = right; i <= left; i++)
^~~~
display.c:12:29: error: ‘numarr’ undeclared (first use in this function)
printf("\n\n\t\t\t\t%d", numarr[i]);
^~~~~~
main.c:3:10: fatal error: conio.h: No such file or directory
#include <conio.h>
^~~~~~~~~
compilation terminated.
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#define SIZE 10
int numarr[SIZE];
int right, left;
//function create is in separate c file named create.c
void create()
{
printf("\n\n\t\t\t\tArray has been created with the size of 10 elements");
}
//function add is in separate c file named add.c
void add()
{
printf("\n\n\t\t\t\t*****ADD Menu*****");
int holder;
if (left == SIZE - 1)
{
printf("\n\n\t\t\t\tQueue is FULL");
}
else
{
printf("\n\t\t\t\tEnter the element you wish to add into queue: ");
scanf_s("%d", &holder);
++left;
numarr[left] = holder;
if (right == -1)
right = 0;
}
}
//function delete is in separate c file delete.c
void delete()
{
int holder;
if (right == -1)
{
printf("\n\n\t\t\t\tERROR! Queue is empty. Please add element before deleting them");
}
else
{
holder = numarr[right];
printf("\n\n\t\t\t\tSUCCESS. Deleted item: %d", holder);
}
if (right == left)
{
right = left = -1;
}
else
{
right++;
}
}
//function display is in separate c file named display.c
void display()
{
int i;
if (right == -1)
{
printf("\n\n\t\t\t\tEmter elements to array to be displayed here!");
}
else
{
printf("\n\n\t\t\t\tDisplay of current elements in queue: ");
for (i = right; i <= left; i++)
printf("\n\n\t\t\t\t%d", numarr[i]);
}
}
//function main is in separate c file named main.c
int main()
{
right = left = -1;
int choice;
do
{
printf("\n\n\t\t\t\tWELCOME TO C PROGRAM ON FIFO \n");
printf("\t\t\t\t1. CREATE an array \n");
printf("\t\t\t\t2. ADD to array \n");
printf("\t\t\t\t3. DELETE from arra \n");
printf("\t\t\t\t4. DISPLAY the array's content \n");
printf("\t\t\t\t5. EXIT the program \n");
printf("\t\t\t\tPlease SELECT from above options: ");
scanf_s("%d", &choice);
switch (choice)
{
case 1:
//create
create();
break;
case 2:
//add
system("cls");
add();
break;
case 3:
//delete
delete();
break;
case 4:
//display
display();
break;
case 5:
exit(0);
}
} while (choice != 5);
return 0;
}``
最佳答案
您正在开发一个程序，该程序已分成几个“模块”。每个模块都是一个 .c 文件。
当您编译所有这些模块时，编译器会为每个 .c 文件生成一个 .o 文件，并不知道它们是相关的。每个编译称为一个“编译单元”。
为了“告诉”编译器源文件是相关的，您可以创建 .h 文件，您可以在 .c 文件中 #include 并且包含关于每个 .c 的其他模块的信息文件需要知道。
关于c - 如何在 Linux 中使用 makefile 编译多个 c 文件 - 出现变量错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53863384/