Initial commit: C language learning code

翁凯C语言/7/字符串函数strcmp.c

@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+#include <stdbool.h>
+#include <string.h>
+
+// !字符串函数string.h
+/*
+	1.string.h
+	  strlen、strcmp、strcpy、strcat、strchr、strstr
+	2.strlen
+	  size_t strlen(const char *s);
+	  返回s的字符串长度（不包括结尾的0)
+	3.strcmp
+	  int strcmp(const char *s1, const char *s2); 比较两个字符串，返回:
+	  0:s1==S2
+	  1:s1>s2
+	  -1:s1<s2
+*/
+
+int my_strcmp(const char *s1, const char *s2)
+{
+	int idx = 0;
+	while (s1[idx]!='\0' && s1[idx] == s2[idx])
+	{
+		idx++;
+	}
+	return s1[idx] - s2[idx];
+}
+
+int main(void)
+{
+	/* strcmp */
+	char s1[] = "abc";
+	char s2[] = "abc";
+	printf("strcmp=%d\n", strcmp(s1, s2));
+
+	char s3[] = "abc";
+	char s4[] = "bbc";
+	printf("strcmp=%d\n", strcmp(s3, s4));
+
+	char s5[] = "abc";
+	char s6[] = "Abc";
+	printf("strcmp=%d\n", strcmp(s5, s6));
+
+	return 0;
+}