diff --git a/solution/0000-0099/0008.String to Integer (atoi)/README.md b/solution/0000-0099/0008.String to Integer (atoi)/README.md
index 87634a3e1f38a..324738cca1c5e 100644
--- a/solution/0000-0099/0008.String to Integer (atoi)/README.md	
+++ b/solution/0000-0099/0008.String to Integer (atoi)/README.md	
@@ -386,6 +386,36 @@ class Solution {
 }
 ```
 
+#### C
+
+```c
+int myAtoi(char* s) {
+    int i = 0;
+
+    while (s[i] == ' ') {
+        i++;
+    }
+
+    int sign = 1;
+    if (s[i] == '-' || s[i] == '+') {
+        sign = (s[i] == '-') ? -1 : 1;
+        i++;
+    }
+
+    int res = 0;
+    while (isdigit(s[i])) {
+        int digit = s[i] - '0';
+        if (res > INT_MAX / 10 || (res == INT_MAX / 10 && digit > INT_MAX % 10)) {
+            return sign == 1 ? INT_MAX : INT_MIN;
+        }
+        res = res * 10 + digit;
+        i++;
+    }
+
+    return res * sign;
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->
diff --git a/solution/0000-0099/0008.String to Integer (atoi)/README_EN.md b/solution/0000-0099/0008.String to Integer (atoi)/README_EN.md
index 05ee6458e6711..bc0c422b89134 100644
--- a/solution/0000-0099/0008.String to Integer (atoi)/README_EN.md	
+++ b/solution/0000-0099/0008.String to Integer (atoi)/README_EN.md	
@@ -374,6 +374,36 @@ class Solution {
 }
 ```
 
+#### C
+
+```c
+int myAtoi(char* s) {
+    int i = 0;
+
+    while (s[i] == ' ') {
+        i++;
+    }
+
+    int sign = 1;
+    if (s[i] == '-' || s[i] == '+') {
+        sign = (s[i] == '-') ? -1 : 1;
+        i++;
+    }
+
+    int res = 0;
+    while (isdigit(s[i])) {
+        int digit = s[i] - '0';
+        if (res > INT_MAX / 10 || (res == INT_MAX / 10 && digit > INT_MAX % 10)) {
+            return sign == 1 ? INT_MAX : INT_MIN;
+        }
+        res = res * 10 + digit;
+        i++;
+    }
+
+    return res * sign;
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->
diff --git a/solution/0000-0099/0008.String to Integer (atoi)/Solution.c b/solution/0000-0099/0008.String to Integer (atoi)/Solution.c
new file mode 100644
index 0000000000000..26f63ab4316e3
--- /dev/null
+++ b/solution/0000-0099/0008.String to Integer (atoi)/Solution.c	
@@ -0,0 +1,25 @@
+int myAtoi(char* s) {
+    int i = 0;
+
+    while (s[i] == ' ') {
+        i++;
+    }
+
+    int sign = 1;
+    if (s[i] == '-' || s[i] == '+') {
+        sign = (s[i] == '-') ? -1 : 1;
+        i++;
+    }
+
+    int res = 0;
+    while (isdigit(s[i])) {
+        int digit = s[i] - '0';
+        if (res > INT_MAX / 10 || (res == INT_MAX / 10 && digit > INT_MAX % 10)) {
+            return sign == 1 ? INT_MAX : INT_MIN;
+        }
+        res = res * 10 + digit;
+        i++;
+    }
+
+    return res * sign;
+}
diff --git a/solution/0000-0099/0009.Palindrome Number/README.md b/solution/0000-0099/0009.Palindrome Number/README.md
index 5293dccce090b..46fbfac16ef77 100644
--- a/solution/0000-0099/0009.Palindrome Number/README.md	
+++ b/solution/0000-0099/0009.Palindrome Number/README.md	
@@ -248,6 +248,24 @@ class Solution {
 }
 ```
 
+#### C
+
+```c
+bool isPalindrome(int x) {
+    if (x < 0 || (x != 0 && x % 10 == 0)) {
+        return false;
+    }
+
+    int y = 0;
+    while (y < x) {
+        y = y * 10 + x % 10;
+        x /= 10;
+    }
+
+    return (x == y || x == y / 10);
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->
diff --git a/solution/0000-0099/0009.Palindrome Number/README_EN.md b/solution/0000-0099/0009.Palindrome Number/README_EN.md
index 8b0ac2e383ca0..712ba430b9d5a 100644
--- a/solution/0000-0099/0009.Palindrome Number/README_EN.md	
+++ b/solution/0000-0099/0009.Palindrome Number/README_EN.md	
@@ -240,6 +240,24 @@ class Solution {
 }
 ```
 
+#### C
+
+```c
+bool isPalindrome(int x) {
+    if (x < 0 || (x != 0 && x % 10 == 0)) {
+        return false;
+    }
+
+    int y = 0;
+    while (y < x) {
+        y = y * 10 + x % 10;
+        x /= 10;
+    }
+
+    return (x == y || x == y / 10);
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->
diff --git a/solution/0000-0099/0009.Palindrome Number/Solution.c b/solution/0000-0099/0009.Palindrome Number/Solution.c
new file mode 100644
index 0000000000000..c13f8cc7947ca
--- /dev/null
+++ b/solution/0000-0099/0009.Palindrome Number/Solution.c	
@@ -0,0 +1,13 @@
+bool isPalindrome(int x) {
+    if (x < 0 || (x != 0 && x % 10 == 0)) {
+        return false;
+    }
+
+    int y = 0;
+    while (y < x) {
+        y = y * 10 + x % 10;
+        x /= 10;
+    }
+
+    return (x == y || x == y / 10);
+}