1、fopen.c:11:29: error: ‘errno’ undeclared (first use in this function); did you mean ‘perror’?
   printf("open:%s",strerror(errno));

未声明错误：加上头文件后者在使用的文件中声明。

2、warning: implicit declaration of function ‘strerror’

警告：  表示strerror函数隐示的声明      解决方法：include 添加对应的头文件。

3、Segmentation fault (core dumped)

段错误：有很多种可能，一般为操作非法地址，数组越界、关闭未打开的文件等问题。

4、fgets.c:13:23: error: too few arguments to function ‘fgets’
  ptintf("gets = %c\n",fgets(fp));
                       ^~~~~
In file included from fgets.c:1:0:
/usr/include/stdio.h:564:14: note: declared here
 extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)

参数传入太少无法使用fgets，想写fgetc来着写错了

5、fgets.c:35:14: error: ‘w’ undeclared (first use in this function)
  if(fput(rec,w) == -1)

传入参数错误fgets第一个参数是要写入的字符第二参数是打开的文件（结构体指针）。

6、fgets.c:35:5: warning: implicit declaration of function ‘fput’; did you mean ‘fputs’? [-Wimplicit-function-declaration]
  if(fput(rec,"w") == -1)
     ^~~~
     fputs

非常经典的警告又少写一个字母，应该是fputc或者fputs

7、fputc: Bad file descriptor

打开的文件按是只读模式，没有写权限。

8、gcc: error: fgrtc.c: No such file or directory
gcc: fatal error: no input files

没有这个文件，可能是打错名字了

9、fread.c:13:14: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration]
  buff=(char*)malloc(100);
              ^~~~~~
fread.c:13:14: warning: incompatible implicit declaration of built-in function ‘malloc’
fread.c:13:14: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’
fread.c:28:5: warning: implicit declaration of function ‘free’ [-Wimplicit-function-declaration]
     free(buff);
     ^~~~
fread.c:28:5: warning: incompatible implicit declaration of built-in function ‘free’
fread.c:28:5: note: include ‘<stdlib.h>’ or provide a declaration of ‘free’

这俩函数都需要调用stdlib库

10、fflush.c:8:3: warning: implicit declaration of function ‘sleep’ [-Wimplicit-function-declaration]
   sleep(1);

没有调用unistd头文件

11、 fseek.c:16:14: error: ‘seek_CUR’ undeclared (first use in this function); did you mean ‘SEEK_CUR’?
  fseek(fp,-2,seek_CUR);
              ^~~~~~~~
              SEEK_CUR

C语言区分大小写。

12、wsystime.c:16:13: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘time_t {aka long int}’ [-Wformat=]

      printf("ctime=%d\n",ctime);

类型不对用强制类型转换

13、/tmp/cc7jpdvG.o: In function `main':
test.c:(.text+0x15): undefined reference to `hello'
test.c:(.text+0x1f): undefined reference to `bye'
collect2: error: ld returned 1 exit status

含义：表示hello函数和bye函数在编译的源码内没有找到实现

解决：实现代码或者找到对应函数的库并且链接它。

14、./test: error while loading shared libraries: libmyheby.so: cannot open shared object file: No such file or directory

含义：可执行文件所使用的动态库找不到

解决办法：

因为动态库会先在系统的lib里找所以找到动态库，添加到/usr/lib里面

//不提倡因为会把自己的lib库搞乱

或者使用export  LD_LIBRARY_PATH=$LD_LIBRARY_PATH:你的动态库目录

添加在~/.bashrc 文件里面

使用source ~/.bashrc 生效。

15、 thread.c: In function ‘main’:
thread.c:13:33: warning: passing argument 3 of ‘pthread_create’ from incompatible pointer type [-Wincompatible-pointer-types]
  ret = pthread_create(&tid,NULL,testThread,NULL);
                                 ^~~~~~~~~~
In file included from thread.c:3:0:
/usr/include/pthread.h:234:12: note: expected ‘void * (*)(void *)’ but argument is of type ‘int * (*)(char *)’
 extern int pthread_create (pthread_t *__restrict __newthread,

意义：表示pthread_create参数3的定义和实际代码不符合，期望的是void * (*)(void *) ，实际的代码是int * (*)(char *)

解决方法：改为pthread_create(&tid,NULL,(void*)testThread,NULL);

16、/tmp/ccWgaZF4.o: In function `main':
thread.c:(.text+0x4b): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status

表示pthread_create这个函数没有实现

解决方法：编译时候加 -lpthread

17、thread.c: In function ‘testThread’:
thread.c:10:35: warning: dereferencing ‘void *’ pointer
     printf("input arg=%d\n",(int) *arg);
                                   ^~~~
thread.c:10:29: error: invalid use of void expression
     printf("input arg=%d\n",(int) *arg);

改成*(int *)arg 或者直接（int）arg

18、

编译错误：

error: ‘ThreadPool {aka struct ThreadPool}’ has no member named ‘head’

意义：ThreadPool 结构体没有head这个成员。

解决：检查是否拼写错误。

19、

error: too few arguments to function ‘pthread_mutex_init’

意思：pthread_mutex_init这个函数参数少了

解决:检查函数的参数，添加对应的参数