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C语言的程序中#xff0c;有很单词多符号和保留字。一些单词符号还有对应的左线性文法。所以我们需要先做出一个单词字符表#xff0c;给出对应的识别码#xff0c;然后跟据对应的表格来写出程序 2.程序设计
程序主要有循环判断构成。不需推理即可产生的符号我…1.分析组成
C语言的程序中有很单词多符号和保留字。一些单词符号还有对应的左线性文法。所以我们需要先做出一个单词字符表给出对应的识别码然后跟据对应的表格来写出程序 2.程序设计
程序主要有循环判断构成。不需推理即可产生的符号我们可以把它包装在函数中返回值为对应的识别码即可。但是有线性文法的则需要单独的一遍推倒才可以得出词法分析结果。对于测试样例我们可以存储到txt文件中使用循环读写可以更高效的测试和输出词法分析结果。最终的结果我们用二元式的形式来表示存储在txt文件中
3.完整程序
#include stdio.h
#include stdlib.h
#include string.hint english(char ch) {if((ch a ch z) || (ch A ch Z)) return 1;else return 0;
}
int number(char ch) {if(ch 0 ch 9) return 1;else return 0;
}
int reserved(char str[]) {if(strcmp(str, void) 0) return 3;else if(strcmp(str, int) 0) return 4;else if(strcmp(str, float) 0) return 5;else if(strcmp(str, double) 0) return 6;else if(strcmp(str, if) 0) return 7;else if(strcmp(str, else) 0) return 8;else if(strcmp(str, for) 0) return 9;else if(strcmp(str, do) 0) return 10;else if(strcmp(str, while) 0) return 11;else if(strcmp(str, break) 0) return 12;else if(strcmp(str, return) 0) return 13;else return 1;
}
int symbol(char ch) {if(ch ;) return 14;else if(ch ,) return 15;else if(ch () return 16;else if(ch )) return 17;else if(ch {) return 18;else if(ch }) return 19;else if(ch [) return 20;else if(ch ]) return 21;else if(ch %) return 22;else if(ch ?) return 23;else if(ch :) return 24;else if(ch \) return 25;else if(ch \) return 26;else if(ch .) return 27;else return 0;
}int main(){for(int i 1; i 4; i){char txt1[] test;char num[6];sprintf(num, %d.txt, i);strcat(txt1, num);char txt2[] analyze;sprintf(num, %d.txt, i);strcat(txt2, num);FILE *fp fopen(txt1, r);FILE *fw fopen(txt2, wt);int flag 0;char ch fgetc(fp); while(!feof(fp)) {char str[32];int j 0;if(ch || ch \t) {ch fgetc(fp);continue;}else if(ch \n){fprintf(fw, \n);ch fgetc(fp);continue;}else if(english(ch)) {str[j] ch;do{ch fgetc(fp);str[j] ch;}while(english(ch)||number(ch));str[j-1] \0;int id reserved(str);fprintf(fw, (%d, %s) , id, str);}else if(number(ch)) {str[j] ch;do{ch fgetc(fp);str[j] ch;}while(number(ch));str[j-1] \0;fprintf(fw, (2, %s) , str);}else if(symbol(ch) ! 0) {fprintf(fw, (%d, %c) , symbol(ch), ch);ch fgetc(fp);}else if(ch ) {ch fgetc(fp);if(ch ) {fprintf(fw, (29, ) );ch fgetc(fp);}else if(ch ) {fprintf(fw, (30, ) );ch fgetc(fp);}else fprintf(fw, (28, ) );}else if(ch ) {ch fgetc(fp);if(ch ) {fprintf(fw, (32, ) );ch fgetc(fp);}else if(ch ) {fprintf(fw, (33, ) );ch fgetc(fp);}else fprintf(fw, (31, ) );}else if(ch !) {ch fgetc(fp);if(ch ) {fprintf(fw, (35, !) );ch fgetc(fp);}else fprintf(fw, (34, !) );}else if(ch ) {ch fgetc(fp);if(ch ) {fprintf(fw, (37, ) );ch fgetc(fp);}else fprintf(fw, (36, ) );}else if(ch /) {ch fgetc(fp);if(ch *) {fprintf(fw, (Start annotate, /*) );do {ch fgetc(fp);if(ch *) {ch fgetc(fp);if(ch /) {fprintf(fw, (End annotate, */) );ch fgetc(fp);break;}}}while(1);}else if(ch /) {fprintf(fw, (annotate, //) );do {ch fgetc(fp);}while(ch ! \n);fprintf(fw, \n);ch fgetc(fp);}else if(ch ) {fprintf(fw, (39, /) );ch fgetc(fp);}else fprintf(fw, (38, /) );}else if(ch ) {ch fgetc(fp);if(ch ) {fprintf(fw, (41, ) );ch fgetc(fp);}else fprintf(fw, (40, ) );}else if(ch |) {ch fgetc(fp);if(ch |) {fprintf(fw, (43, ||) );ch fgetc(fp);}else fprintf(fw, (42, |) );}else if(ch ) {ch fgetc(fp);if(ch ) {fprintf(fw, (46, ) );ch fgetc(fp);}else if(ch ) {fprintf(fw, (45 ) );ch fgetc(fp);}else fprintf(fw, (44, ) );}else if(ch -) {ch fgetc(fp);if(ch ) {fprintf(fw, (49, -) );ch fgetc(fp);}else if(ch -) {fprintf(fw, (48, --) );ch fgetc(fp);}else fprintf(fw, (47, -) );}else if(ch *) {ch fgetc(fp);if(ch ) {fprintf(fw, (51, *) );ch fgetc(fp);}else fprintf(fw, (50, *) );}else if(ch \\) {ch fgetc(fp);if(ch n) {ch fgetc(fp);}}else {fprintf(fw, Undefined symbol!);printf(test%d: Undefined symbol!\n, i); flag 1;break;}}fclose(fp);fclose(fw);if(flag) continue;printf(test%d: Finish analyzing.\n, i);}
} 4.测试运行
其中一个测试样例剩余的大家可以自主编写
void test1() {int a 5, b 10;if (a b) {printf(a is greater than b);} else if (a b) {printf(b is greater than a);} else {printf(a and b are equal);}for (int i 0; i 5; i) {printf(%d , i);}printf(\n);int arr[5] {1, 2, 3, 4, 5};int sum 0;for (int i 0; i 5; i) {sum arr[i];}printf(The sum of the array is: %d\n, sum);return 0;
}运行结果:
(3, void) (1, test1) (16, () (17, )) (18, {)
(4, int) (1, a) (36, ) (2, 5) (15, ,) (1, b) (36, ) (2, 10) (14, ;)
(7, if) (16, () (1, a) (28, ) (1, b) (17, )) (18, {)
(1, printf) (16, () (26, ) (1, a) (1, is) (1, greater) (1, than) (1, b) (26, ) (17, )) (14, ;)
(19, }) (8, else) (7, if) (16, () (1, a) (31, ) (1, b) (17, )) (18, {)
(1, printf) (16, () (26, ) (1, b) (1, is) (1, greater) (1, than) (1, a) (26, ) (17, )) (14, ;)
(19, }) (8, else) (18, {)
(1, printf) (16, () (26, ) (1, a) (1, and) (1, b) (1, are) (1, equal) (26, ) (17, )) (14, ;)
(19, }) (9, for) (16, () (4, int) (1, i) (36, ) (2, 0) (14, ;) (1, i) (31, ) (2, 5) (14, ;) (1, i) (45 ) (17, )) (18, {)
(1, printf) (16, () (26, ) (22, %) (1, d) (26, ) (15, ,) (1, i) (17, )) (14, ;)
(19, })
(1, printf) (16, () (26, ) (26, ) (17, )) (14, ;) (4, int) (1, arr) (20, [) (2, 5) (21, ]) (36, ) (18, {) (2, 1) (15, ,) (2, 2) (15, ,) (2, 3) (15, ,) (2, 4) (15, ,) (2, 5) (19, }) (14, ;)
(4, int) (1, sum) (36, ) (2, 0) (14, ;)
(9, for) (16, () (4, int) (1, i) (36, ) (2, 0) (14, ;) (1, i) (31, ) (2, 5) (14, ;) (1, i) (45 ) (17, )) (18, {)
(1, sum) (46, ) (1, arr) (20, [) (1, i) (21, ]) (14, ;)
(19, })
(1, printf) (16, () (26, ) (1, The) (1, sum) (1, of) (1, the) (1, array) (1, is) (24, :) (22, %) (1, d) (26, ) (15, ,) (1, sum) (17, )) (14, ;) (13, return) (2, 0) (14, ;)
(19, })
