1.strcat()、strncat()字符串追加函数
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> #include<stdlib.h> #include<math.h> #include<string.h> int main0201()//字符串追加函数，注意字符串1有足够空间容纳字符串2 { char a[100] = "abc"; char b[100] = "defg"; strcat(a, b);//将字符串b追加到a之后，并输出a printf("%s\n", a); return 0; } int main0202() { char a[100] = "abc"; char b[100] = "defg"; strncat(a, b,1);//将字符串b追加到a之后，并输出a printf("%s\n", a); return 0; }
2.strcmp()、strncmp()字符串比较函数
#include<stdio.h> int main0301()//字符串比较 { char a[100] = "abc"; char b[100] = "abcd"; if (strcmp(a, b)==0)//比较a，b是否相同 printf("相同"); else printf("不同"); return 0; } int main0302()//字符串有限比较 { char a[100] = "abc"; char b[100] = "abcd"; if (strncmp(a, b,4) == 0)//比较a，b的前n个字符是否相同 printf("相同"); else printf("不同"); return 0; }
3.strcpy()字符串拷贝函数
#include<stdio.h> int main0401()//字符串拷贝，将b拷贝到a中并覆盖a内容 { char a[100] = "abc"; char b[100] = "12345"; strcpy(a, b); printf("%s\n", a); return 0; } int main0402() { char a[100] = "abc"; char b[100] = "12345"; strncpy(a, b,sizeof(a)-1);//将a字符串放满 printf("%s\n", a); return 0; }
4.sprintf()格式化输入到字符串函数
#include<stdio.h> int main0501() { char a[100]; sprintf(a, "%s", "hello world"); printf("%s\n", a); return 0; }
5.sscanf()字符串读取函数
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> #include<stdlib.h> #include<math.h> #include<string.h> int main0601() { char a[100] = "10+10"; int b; int c; sscanf(a, "%d+%d", &b, &c); printf("%d+%d=%d\n", b, c, b + c); } int main0602() { char a[100] = "43*25="; int i, j; char c; sscanf(a, "%d%c%d=", &i, &c, &j); int res=0; switch (c) { case'+': res = i + j; break; case'-': res = i - j; break; case'*': res = i * j; break; case'/': res = i / j; break; default: res = 0; } printf("%d%c%d=%d", i, c, j, res); }
6.strchr()字符查找函数
#include<stdio.h> #include<stdlib.h> int main0701() { char a[100] = "hello world"; char* s; s = strchr(a, 'l'); if(s!=NULL) printf("%s\n", s); return 0; }
7.strstr()字符串中查找子串
#include<stdio.h> #include<stdlib.h> int main0801()//字符串中查找子串 { char a[100] = "hello world"; char *s; s = strstr(a, "llo"); printf("%s\n", s); return 0; }
8.strtok()字符串分割函数
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> #include<stdlib.h> #include<math.h> #include<string.h> int main0901() { char a[100] = "abc_bce_123_456"; char* s; s = strtok(a, "_"); printf("%s\n", s); s = strtok(NULL, "_");//第二次调用时，参数写NULL printf("%s\n", s); s = strtok(NULL, "_"); printf("%s\n", s); return 0; } int main0902() { char a[100] = "abc_bce_123_456"; char* s; s = strtok(a, "_"); while (s) { printf("%s\n", s); s = strtok(NULL, "_"); } return 0; }
9.atoi函数
#include<stdio.h> #include<stdlib.h> int main10_01()//atoi() { char a[] = "123";//将字符串转化为整数 atoi() char b[] = "456"; int i = atoi(a) + atoi(b); printf("%d\n", i); return 0; }
10.atof函数
#include<stdio.h> #include<stdlib.h> int main10_02()//atof { char a[100] = "3.555"; double f = atof(a); printf("%f\n", f); return 0; }
11.将一个数字追加到字符串之后
#include<stdio.h> #include<stdlib.h> int main10_03()//将100追加到abc之后 { char a[100] = "222"; char str1[100] = "abc"; int num = 100; sprintf(a, "%d", num); strcat(str1, a); printf("%s\n", str1); return 0; }
12.将字符串中的值求出
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> #include<stdlib.h> #include<math.h> #include<string.h> int main011() { char a[100] = "15+20=;22-11=;13*50=;70/20="; char b[100] = {0}; char* p = strtok(a, ";"); while (p) { int i, j; char c; int sum = 0; sscanf(p, "%d%c%d=", &i, &c, &j); switch (c) { case '+': sum = i + j; break; case '-': sum = i - j; break; case '*': sum = i * j; break; case '/': sum = i / j; break; default: sum = NULL; break; } char temp[10] = {0}; sprintf(temp, "%s%d;", p ,sum); strcat(b, temp); p = strtok(NULL, ";"); } strcpy(a, b); printf("%s\n", a); return 0; }
13.z自定义函数的调用和使用
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> #include<stdlib.h> #include<math.h> #include<string.h> int add(int a, int b)//自定义函数 { return a + b; } void test()//定义一个自定义函数，没有返回值也没有参数 { printf("test\n"); } void test1();//声明需调用的函数 void test2(int a); int mmax(int a, int b) { return (a > b) ? a : b; } int main012() { int i = 2; int j = 3; int c = add(i, j);//调用函数 printf("%d\n", c); test();//调用一个没参数，没返回值的函数 test1(); test2(i);//i是实参,实参可以是变量、常量也可以是表达式 int k=mmax(i, j); printf("%d\n", k); return 0; } void test1() { printf("test1\n"); } void test2(int a)//其中a为形参 { printf("a=%d\n", a); }
14.递归函数
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> void test3(int n) { if (n < 10) { test3(n + 1); } printf("n=%d\n", n); } int main14_01() { int a = 0; test3(a); return 0; }
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> int age(int n)//n个人，后面的人比前面的人大2岁，求第n个人多大，之一个10岁 { if (n == 1)//递归结束条件 return 10; return age(n - 1) + 2; } int main14_02() { int a = 5; printf("%d\n", age(a)); return 0; }
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> void to_bin(unsigned int n)//将一个十进制数转换为二进制 { int i = n % 2; if (n >= 2) { to_bin(n / 2); } printf("%d\n", i); } int main14_03() { int a = 13; scanf("%d", &a); to_bin(a); return 0; }
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> char hex_char(unsigned int n)//将十进制数转换为16进制 { switch (n) { case 1: return '1'; case 2: return '2'; case 3: return '3'; case 4: return '4'; case 5: return '5'; case 6: return '6'; case 7: return '7'; case 8: return '8'; case 9: return '9'; case 10: return 'a'; case 11: return 'b'; case 12: return 'c'; case 13: return 'd'; case 14: return 'e'; case 15: return 'f'; } return '0'; } void to_hex(unsigned int n) { int i = n % 16; if (n >= 16) to_hex(n / 16); printf("%c", hex_char(i)); } int main14_04() { int a; scanf("%d", &a); to_hex(a); printf("\n"); return 0; }
#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> int fib(int n)////斐波那契数列 0,1,1,2,3,5,8,13,21,34,55 { if (n == 1) return 1; if (n == 2) return 2; return fib(n - 1) + fib(n - 2); } int main() { int i; for (i = 1; i < 20; i++) { printf("%d\n", fib(i)); } return 0; }
