diff --git a/lab1/10215501408.c b/lab1/10215501408.c
new file mode 100644
index 0000000..244286f
--- /dev/null
+++ b/lab1/10215501408.c
@@ -0,0 +1,59 @@
+#include "stdio.h"
+#include "stdlib.h"
+#include "time.h"
+#include "math.h"
+#include "string.h"
+
+/**
+ * @brief generate a file consists of 50000 lines of words, 
+ *        half line has a substring "computer", and is repeated.
+ *        the clone one is stripped of "computer".
+ *        
+ *        0 ~ 9 : 48 ~ 57
+ *        a ~ z : 97 ~ 122
+ * 
+ */
+
+
+void file_create(const char *_addr)
+{
+    FILE *file = fopen(_addr, "w");
+    size_t line = 250000u;
+    srand(time(NULL));
+
+    // char *str = NULL;
+    for (size_t i = 0; i < line; i++) {
+        // str = (char *)malloc(abs(rand())%20 * sizeof(char));
+        char str[abs(rand())%100+1];
+        for (size_t j = 0; j < strlen(str); j++) {
+            if (abs(rand()) % 2 == 0) 
+                str[j] = abs(rand())%10 + 48;
+            else
+                str[j] = abs(rand())%26 + 97;
+        }
+        strcat(str, "computer\n");
+        fputs(str, file);
+        fputs(str, file);
+        // free(str);
+    }   
+
+    fclose(file);
+}
+
+void file_show() 
+{
+    FILE *file = fopen("words.txt", "r");
+    int ch;
+
+    while ((ch = fgetc(file)) != '\n') {
+        printf("%c", ch);
+    }
+
+    fclose(file);
+}
+
+int main()
+{
+    file_create("words.txt");
+    return 0;
+}
\ No newline at end of file
diff --git a/lab1/10215501408.txt b/lab1/10215501408.txt
new file mode 100644
index 0000000..ee304c4
--- /dev/null
+++ b/lab1/10215501408.txt
@@ -0,0 +1,2 @@
+this is a file with the 10215501408.c
+