diff --git a/c-cpp/15_bsearch/bsearch_c/sqrt.c b/c-cpp/15_bsearch/bsearch_c/sqrt.c
new file mode 100644
index 0000000..7c7c3d4
--- /dev/null
+++ b/c-cpp/15_bsearch/bsearch_c/sqrt.c
@@ -0,0 +1,53 @@
+/*************************************************************************
+ > File Name: sqrt.c
+ > Author:  jinshaohui
+ > Mail:    jinshaohui789@163.com
+ > Time:    18-10-31
+ > Desc:    
+ ************************************************************************/
+#include<stdio.h>
+#include<string.h>
+#include<stdlib.h>
+#include<assert.h>
+
+
+/*求解精度设置*/
+#define E 0.000001 
+double mybsearch(double num)
+{
+	double start = 1.0;
+	double end = num;
+    double mid = 0.0;
+	while(1)
+	{
+	    mid = (start + end)/2;
+        if(((mid*mid - num) <= E) && ((mid*mid - num) >= -E))
+		{
+			return mid;
+		}
+
+		if ((mid*mid - num) > E)
+		{
+			end = mid;
+		}
+		else
+		{
+			start = mid;
+		}
+ 	}
+
+	return 0;
+}
+	
+
+int main()
+{
+	double num = 0.0;
+
+	/*这里需要注意：double的输入方式*/
+	scanf("%lf",&num);
+	printf("\r\n num %lf的平方根是%lf",num,mybsearch(num));
+
+	return 0;
+}
+