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词法分析
1 #include <iostream> 2 #include <fstream> 3 #define max 500 4 using namespace std; 5 6 char pr[max]; 7 int ll,rr; 8 int n = 0; 9 int m = 0; 10 char * keyw[5] = { "if","else","main","int","return"}; 11 12 ofstream outfile; 13 14 15 16 typedef struct identifier { 17 char token[8]; 18 identifier *next; 19 }idtf; 20 21 typedef struct number { 22 int data; 23 number *next; 24 }num; 25 26 num *number = (num *)malloc(sizeof(num)); 27 idtf *idtfier = (idtf *)malloc(sizeof(idtf)); 28 29 num *p = number; 30 idtf *q = idtfier; 31 32 int ch = ‘0‘; 33 34 int infile() { 35 FILE * pFile; 36 long lSize; 37 38 size_t result; 39 40 pFile = fopen("program.txt", "rb"); // 打开文件 41 if (pFile == NULL) { fputs("File error", stderr); exit(1); } 42 43 // 获取文件大小: 44 fseek(pFile, 0, SEEK_END); 45 lSize = ftell(pFile); 46 rewind(pFile); 47 48 result = fread(pr, 1, lSize, pFile); 49 if (result != lSize) { fputs("Reading error", stderr); exit(3); } 50 51 52 for (int j = 0; j<lSize; j++) { 53 cout << pr[j] ; 54 } 55 fclose(pFile); 56 return 0; 57 } 58 59 60 void scanner() { 61 62 ch = pr[n++]; 63 while (ch == ‘ ‘) 64 { 65 ch = pr[n++]; 66 67 } 68 int i = 0; 69 if ((ch >= ‘a‘&&ch <= ‘z‘) ||( ch >= ‘A‘&&ch <= ‘Z‘)) {//识别标识符 70 idtf *s = (idtf *)malloc(sizeof(idtf)); 71 72 while ((ch >= ‘a‘&&ch <= ‘z‘) || (ch >= ‘A‘&&ch <= ‘Z‘) ||( ch >= ‘0‘ && ch <=‘9‘)) { 73 s->token[i++] = ch; 74 ch = pr[n++]; 75 } 76 s->token[i++] = ‘\0‘; 77 n--; 78 for (i = 0; i < 5; i++) { 79 if (strcmp(s->token, keyw[i]) == 0) { 80 ll = 14; 81 rr = i+1; 82 return; 83 } 84 } 85 86 87 i = 0; 88 ll = 0; 89 idtf *cmp = idtfier; 90 while (cmp->next != NULL) { 91 if (strcmp(s->token, cmp->next->token) == 0) { 92 rr = i+1; 93 return; 94 } 95 i++; 96 cmp = cmp->next; 97 } 98 q->next = s; 99 s->next = NULL; 100 q = s; 101 rr = i + 1; 102 103 return; 104 105 106 } 107 108 109 else if (ch >= ‘0‘ && ch <= ‘9‘) {//判断是否为数字常量 110 num *s = (num *)malloc(sizeof(num)); 111 int sum=0; 112 while (ch >= ‘0‘ && ch <= ‘9‘) { 113 sum = 10 * sum + ch - 48; 114 ch = pr[n++]; 115 116 } 117 118 n--; 119 s->data =http://www.mamicode.com/ sum; 120 p->next = s; 121 s->next = NULL; 122 p = s; 123 ll = 1; m++;rr = m; 124 125 } 126 else switch (ch) { 127 case ‘=‘: {ll = 2; rr = ‘=‘; return; } 128 case ‘(‘: {ll = 3; rr = ‘(‘; return; } 129 case ‘)‘: {ll = 4; rr = ‘)‘; return; } 130 case ‘{‘: {ll = 5; rr = ‘{‘; return; } 131 case ‘}‘: {ll = 6; rr = ‘}‘; return; } 132 case ‘+‘: {ll = 7; rr = ‘+‘; return; } 133 case ‘-‘: {ll = 8; rr = ‘-‘; return; } 134 case ‘*‘: {ll = 9; rr = ‘*‘; return; } 135 case ‘/‘: {ll = 10; rr = ‘/‘; return; } 136 case ‘%‘: {ll = 11; rr = ‘%‘; return; } 137 case ‘,‘: {ll = 12; rr = ‘,‘; return; } 138 case ‘;‘: {ll = 13; rr = ‘;‘; return; } 139 default: {ll = -1; break; } 140 } 141 142 } 143 144 145 146 147 148 int main() { 149 number->next = NULL; 150 idtfier->next = NULL; 151 152 infile(); 153 outfile.open("out.txt"); 154 while (ch != ‘#‘) { 155 scanner(); 156 if (ll == 1 || ll == 0||ll==14) { 157 outfile << "<" << ll << "," << rr << ">" << endl; 158 } 159 else if (ll >= 2 && ll <= 13) { 160 char rc = rr; 161 outfile << "<" << ll << "," << rc << ">" << endl; 162 } 163 } 164 outfile.close(); 165 166 167 168 169 system("PAUSE"); 170 return 0; 171 172 }
词法分析
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