下面使用代码的方式说明,较为简单,请自行阅读. ```C #include <stdio.h> #include <stdlib.h> #include <math.h> #define MAX_BYTES 64 int read_int(FILE *file,char *buffer) { fgets(buffer,MAX_BYTES,file); return atoi(buffer); } void main(int argc,char *argv[]) { char * file1 = argv[1]; char * file2 = argv[2]; char buffer[MAX_BYTES]; FILE *fd1 = fopen(file1,"r"); if(fd1 == NULL) { printf("Can not open file %s.\n",file1); return; } FILE *fd2 = fopen(file2,"r"); if(fd2 == NULL) { printf("Can not open file %s.\n",file2); return; } for(int i = 1;!feof(fd1);i++) { int outer = read_int(fd1,buffer); for(int j=1;!feof(fd2);j++) { int inner = read_int(fd2,buffer); if(outer == inner) { printf("Value : %d,outer line : %d,inner line : %d\n",outer,i,j); } } rewind(fd2); } fclose(fd2); fclose(fd1); } ``` 运行输出: ```Shell helloworld@DESKTOP-BRAEUTR /d/work/source/c/join $ time ./nested.exe a.csv b.csv Value : 51,outer line : 1,inner line : 25646 Value : 51,outer line : 1,inner line : 35302 Value : 51,outer line : 1,inner line : 39994 Value : 51,outer line : 1,inner line : 69241 Value : 51,outer line : 1,inner line : 69614 Value : 51,outer line : 1,inner line : 72504 Value : 51,outer line : 1,inner line : 72851 Value : 51,outer line : 1,inner line : 78530 Value : 51,outer line : 1,inner line : 88119 ...... ```