进程终止介绍

echo $?

#incldue <stdio.h>

int main()
{
	printf("hello world\n");
	return 0;
}

ls hahahaha

#include <stdio.h>
#include <string.h>

int main()
{
	printf("%s",strerror(2));
	return 0;
}

//打印结果
//No such file or directory

#include <stdio.h>
#include <string.h>
int main()
{
    int i = 0;
    for(i = 0;i<200;++i){
        printf("%s\n",strerror(i));
    }
    return 0;
}
//打印结果
/*
0: Success
1: Operation not permitted
2: No such file or directory
3: No such process
4: Interrupted system call
5: Input/output error
6: No such device or address
7: Argument list too long
8: Exec format error
9: Bad file descriptor
10: No child processes
11: Resource temporarily unavailable
12: Cannot allocate memory
13: Permission denied
14: Bad address
15: Block device required
16: Device or resource busy
17: File exists
18: Invalid cross-device link
19: No such device
20: Not a directory
21: Is a directory
22: Invalid argument
23: Too many open files in system
24: Too many open files
25: Inappropriate ioctl for device
26: Text file busy
27: File too large
28: No space left on device
29: Illegal seek
30: Read-only file system
31: Too many links
32: Broken pipe
33: Numerical argument out of domain
34: Numerical result out of range
35: Resource deadlock avoided
36: File name too long
37: No locks available
38: Function not implemented
39: Directory not empty
40: Too many levels of symbolic links
41: Unknown error 41
42: No message of desired type
43: Identifier removed
44: Channel number out of range
45: Level 2 not synchronized
46: Level 3 halted
47: Level 3 reset
48: Link number out of range
49: Protocol driver not attached
50: No CSI structure available
51: Level 2 halted
52: Invalid exchange
53: Invalid request descriptor
54: Exchange full
55: No anode
56: Invalid request code
57: Invalid slot
58: Unknown error 58
59: Bad font file format
60: Device not a stream
61: No data available
62: Timer expired
63: Out of streams resources
64: Machine is not on the network
65: Package not installed
66: Object is remote
67: Link has been severed
68: Advertise error
69: Srmount error
70: Communication error on send
71: Protocol error
72: Multihop attempted
73: RFS specific error
74: Bad message
75: Value too large for defined data type
76: Name not unique on network
77: File descriptor in bad state
78: Remote address changed
79: Can not access a needed shared library
80: Accessing a corrupted shared library
81: .lib section in a.out corrupted
82: Attempting to link in too many shared libraries
83: Cannot exec a shared library directly
84: Invalid or incomplete multibyte or wide character
85: Interrupted system call should be restarted
86: Streams pipe error
87: Too many users
88: Socket operation on non-socket
89: Destination address required
90: Message too long
91: Protocol wrong type for socket
92: Protocol not available
93: Protocol not supported
94: Socket type not supported
95: Operation not supported
96: Protocol family not supported
97: Address family not supported by protocol
98: Address already in use
99: Cannot assign requested address
100: Network is down
101: Network is unreachable
102: Network dropped connection on reset
103: Software caused connection abort
104: Connection reset by peer
105: No buffer space available
106: Transport endpoint is already connected
107: Transport endpoint is not connected
108: Cannot send after transport endpoint shutdown
109: Too many references: cannot splice
110: Connection timed out
111: Connection refused
112: Host is down
113: No route to host
114: Operation already in progress
115: Operation now in progress
116: Stale file handle
117: Structure needs cleaning
118: Not a XENIX named type file
119: No XENIX semaphores available
120: Is a named type file
121: Remote I/O error
122: Disk quota exceeded
123: No medium found
124: Wrong medium type
125: Operation canceled
126: Required key not available
127: Key has expired
128: Key has been revoked
129: Key was rejected by service
130: Owner died
131: State not recoverable
132: Operation not possible due to RF-kill
133: Memory page has hardware error
134: Unknown error 134
135: Unknown error 135
136: Unknown error 136
137: Unknown error 137
138: Unknown error 138
139: Unknown error 139
......
*/

#include <stdio.h>

enum{
    SUCCESS = 0,
    DIV_ZERO,
    MOD_ZERO,
};

int errcode = SUCCESS;

int div_cal(int a,int b)
{
    if(b == 0){
        errcode = DIV_ZERO;
        return -1;
    }
    else{
        return a/b;
    }
}
//翻译错误码
char* traErr(int error)
{
    switch(error)
    {
        case SUCCESS:
            return "SUCCESS";
        case DIV_ZERO:
            return "DIV_ZERO";
        case MOD_ZERO:
            return "MOD_ZERO";
        default:
            return NULL;
    }
}

int main()
{
    int ans = div_cal(10,2);
    printf("answer: %d Error:%s\n",ans,traErr(errcode));
    int ans2 = div_cal(10,0);
    printf("answer:%d Error:%s\n",ans2,traErr(errcode));

    return 0;
}

打印结果：
answer: 5 Error:SUCCESS
answer:-1 Error:DIV_ZERO

#include <stdio.h>
#include <unistd.h>

int main()
{
    while(1){
        printf("i am a process,pid = %d\n",getpid());
        sleep(1);
    }
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
int main()
{
    printf("hahah"); //注意不要写\n，使用\n会直接刷新数据
    exit(1);
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main()
{
    printf("hahah");
    _exit(1);
    return 0;
}