C语言知识总结1如何接收字符串使用字符数组使用指针。（可以随意改变字符的长度，而不用向数组一样要同时改变数组的长度）#include<stdio.h>intmain(){chara[10]="yangtao";char*ab="jfksdjfklsjfkj";printf("%s\n",a);printf("%s",ab);}2系统自带的字符串处理函数(处理字符串数据)#include<stdio.h>#include<string.h>intmain(){inti;char*ab="jfksdjfklsjfkj";i=strlen(ab);printf("共有的字符串个数\n");printf("%d",i);}函数原型是：intstrlen(*p)3ASC码表#include<stdio.h>#include<string.h>intmain(){charkk='a';intk=65;printf("%c",k);printf("%d",kk);}这就是为什么电脑能处理键盘上字符的原因应用大小写字母的转换#include<stdio.h>#include<string.h>intmain(){charKK='A';charkkk='b';KK=KK+32;kkk=kkk-32;printf("%c\n",KK);printf("%c\n",kkk);}4字符串高级应用读取SQL语句。引申出SQL语句5scanf()语句从键盘输入时需要按括号里面的格式输入才不会出错。6验证码忽略大小写的实现Strcmp{}#include<stdio.h>#include<string.h>voidzhuanghuangdaxie(char*P);voidmain(){charshuru[100];charyanzhengma[100]="hduFESF";printf("此功能是实现忽略大小写的验证码验证功能\n");printf("验证码为:hduFESF\n");printf("请输入验证码：\n");scanf("%s",shuru);zhuanghuangdaxie(shuru);zhuanghuangdaxie(yanzhengma);while(1){if(!strcmp(shuru,yanzhengma)){printf("输入成功\n");}else{printf("输入失败\n");}printf("请输入验证码：\n");scanf("%s",shuru);}}voidzhuanghuangdaxie(char*P){intk=0;while(P[k]!='\0'){if(P[k]>96&&P[k]<123){P[k]=P[k]-32;}k++;}}7结构体其实是一种新的数据类型Structstudent{}；一样的结构：IntaStructstudenta类型变量名Char*pStructstudent*p举例：基本框架Structshuju{Structshujua;a=creat();Print(a);};Structshujucreat(){}Voidprint(structfushuf){}复数相加#include<stdio.h>#include<string.h>structfushu{intreal;intimage;};structfushucreatfushu();voidadd(structfushuf1,structfushuf2);voidprint(structfushuf);voidmain(){structfushufu1,fu2;printf("请你创建第一个复数\n");fu1=creatfushu();print(fu1);printf("请你创建第二个复数\n");fu2=creatfushu();print(fu2);printf("实现两个复数相加\n");add(fu1,fu2);return0;}structfushucreatfushu(){structfushua;printf("请输入一个数作为复数的实部\n");scanf("%d",&(a.real));printf("请输入一个数作为复数的虚部\n");scanf("%d",&(a.image)