diff --git a/2207/C语言同步练习源码/8-文件-3.c b/2207/C语言同步练习源码/8-文件-3.c
new file mode 100644
index 0000000..0f1d3d3
--- /dev/null
+++ b/2207/C语言同步练习源码/8-文件-3.c
@@ -0,0 +1,20 @@
+#include <stdio.h>
+
+int main(){
+	char str[100];
+	char *p = str;
+	FILE *fp;
+	fp = fopen("test.dat", "w");
+	gets(str);
+	
+	while(*p != '\0'){
+		if(*p >= 'a' && *p <= 'z'){
+			*p-=32;
+		}
+		p++;
+	}
+	fputs(str, fp);
+	fclose(fp);
+	return 0;
+}
+
diff --git a/2207/C语言同步练习源码/test.dat b/2207/C语言同步练习源码/test.dat
new file mode 100644
index 0000000..a815426
--- /dev/null
+++ b/2207/C语言同步练习源码/test.dat
@@ -0,0 +1 @@
+ADFADFAAAFDAFDSFSDF
\ No newline at end of file
diff --git a/2207/C语言同步练习答案.md b/2207/C语言同步练习答案.md
index 56e2c34..e5c0a04 100644
--- a/2207/C语言同步练习答案.md
+++ b/2207/C语言同步练习答案.md
@@ -1089,5 +1089,28 @@ int main(){
 
 ![image-20250227231516025](https://yp.smallkun.cn/markdown/image-20250227231516025.png!compress)
 
+```c
+#include <stdio.h>
+
+int main(){
+	char str[100];
+	char *p = str;
+	FILE *fp;
+	fp = fopen("test.dat", "w");
+	gets(str);
+	
+	while(*p != '\0'){
+		if(*p >= 'a' && *p <= 'z'){
+			*p-=32;
+		}
+		p++;
+	}
+	fputs(str, fp);
+	fclose(fp);
+	return 0;
+}
+
+```
+