1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
#include "../command.h"
static long cast_long(const char* arg) {
char* end;
long l = strtol(arg, &end, 10);
if (end == arg) {
return 0;
} else {
return l;
}
}
static double cast_double(const char* arg) {
char* end;
double d = strtod(arg, &end);
if (end == arg) {
return 0.0;
} else {
return d;
}
}
#define NUMBER(name, type, arg) \
long l = cast_long(arg); \
type* t = (type*) &l; \
type name = *t;
static void handle_percent(char n, const char* arg) {
switch (n) {
case 'd':
case 'z': {
NUMBER(i, int, arg)
printf("%d", i);
break;
}
case 'u': {
NUMBER(u, unsigned int, arg);
printf("%u", u);
break;
}
case 'f': {
double d = cast_double(arg);
printf("%lf", d);
break;
}
case 'c': {
putchar(arg[0]);
break;
}
case 's': {
printf("%s", arg);
break;
}
default: {
putchar('%');
putchar(n);
}
}
}
static void handle_slash(char n) {
switch (n) {
case 'n':
putchar('\n');
break;
case 't':
putchar('\t');
break;
case 'v':
putchar('\v');
break;
case 'b':
putchar('\b');
break;
case 'f':
putchar('\f');
break;
case 'e':
putchar('\e');
case 'a':
putchar('\a');
break;
case '"':
putchar('"');
break;
case 'c':
exit(EXIT_SUCCESS);
default:
putchar('\\');
putchar(n);
}
}
static void help(void) {
printf("Usage printf FORMAT [ARG]...\n\n");
printf("Format and print ARG(s) according to FORMAT (a-la C prinf)\n");
}
COMMAND(print) {
if (argc < 1) {
error("usage: printf FORMAT [ARG]...\n");
}
parse_help(argc, argv, help);
size_t index = 0;
int arg_index = 0;
while (true) {
char c = argv[0][index];
index++;
if (c == '\0') break;
if (c != '%' && c != '\\') {
putchar(c);
continue;
}
char n = argv[0][index];
index++;
char* arg = NULL;
if (arg_index < argc) {
arg = argv[arg_index + 1];
}
if (c == '%') {
handle_percent(n, arg);
} else {
handle_slash(n);
}
arg_index++;
}
return EXIT_SUCCESS;
}
|
