c语言中，怎么定义一个随意大小的字符串呢？ c语言中怎么实现任意长度字符串输入
c\u8bed\u8a00\u4e2d,\u600e\u4e48\u6837\u5b9a\u4e49\u4e00\u4e2a\u5b57\u7b26\u4e32\u53d8\u91cf1\u3001\u5b9a\u4e49\u53d8\u91cf\u5b57\u7b26\u4e32\u3002
char str[200];
\u5b9a\u4e49\u4e00\u4e2a\u957f\u5ea6\u6700\u5927\u4e3a200\u5b57\u7b26\u7684\u5b57\u7b26\u4e32\u3002
2\u3001\u5b9a\u4e49\u5e38\u91cf\u5b57\u7b26\u4e32\u3002
\u7531\u4e8e\u5e38\u91cf\u5b57\u7b26\u4e32\u5b58\u50a8\u5728\u5e38\u91cf\u7a7a\u95f4\u4e2d\uff0c\u6240\u4ee5\u53ea\u9700\u8981\u5b9a\u4e49\u4e00\u4e2a\u6307\u9488\uff0c\u6307\u5411\u8be5\u5730\u5740\u5373\u53ef\u3002\u5982char *s = "test string"\u3002
\u62d3\u5c55\u8d44\u6599c\u8bed\u8a00:
C\u8bed\u8a00\u662f\u4e00\u95e8\u901a\u7528\u8ba1\u7b97\u673a\u7f16\u7a0b\u8bed\u8a00\uff0c\u5e94\u7528\u5e7f\u6cdb\u3002C\u8bed\u8a00\u7684\u8bbe\u8ba1\u76ee\u6807\u662f\u63d0\u4f9b\u4e00\u79cd\u80fd\u4ee5\u7b80\u6613\u7684\u65b9\u5f0f\u7f16\u8bd1\u3001\u5904\u7406\u4f4e\u7ea7\u5b58\u50a8\u5668\u3001\u4ea7\u751f\u5c11\u91cf\u7684\u673a\u5668\u7801\u4ee5\u53ca\u4e0d\u9700\u8981\u4efb\u4f55\u8fd0\u884c\u73af\u5883\u652f\u6301\u4fbf\u80fd\u8fd0\u884c\u7684\u7f16\u7a0b\u8bed\u8a00\u3002
\u5c3d\u7ba1C\u8bed\u8a00\u63d0\u4f9b\u4e86\u8bb8\u591a\u4f4e\u7ea7\u5904\u7406\u7684\u529f\u80fd\uff0c\u4f46\u4ecd\u7136\u4fdd\u6301\u7740\u826f\u597d\u8de8\u5e73\u53f0\u7684\u7279\u6027\uff0c\u4ee5\u4e00\u4e2a\u6807\u51c6\u89c4\u683c\u5199\u51fa\u7684C\u8bed\u8a00\u7a0b\u5e8f\u53ef\u5728\u8bb8\u591a\u7535\u8111\u5e73\u53f0\u4e0a\u8fdb\u884c\u7f16\u8bd1\uff0c\u751a\u81f3\u5305\u542b\u4e00\u4e9b\u5d4c\u5165\u5f0f\u5904\u7406\u5668\uff08\u5355\u7247\u673a\u6216\u79f0MCU\uff09\u4ee5\u53ca\u8d85\u7ea7\u7535\u8111\u7b49\u4f5c\u4e1a\u5e73\u53f0\u3002
\u4e8c\u5341\u4e16\u7eaa\u516b\u5341\u5e74\u4ee3\uff0c\u4e3a\u4e86\u907f\u514d\u5404\u5f00\u53d1\u5382\u5546\u7528\u7684C\u8bed\u8a00\u8bed\u6cd5\u4ea7\u751f\u5dee\u5f02\uff0c\u7531\u7f8e\u56fd\u56fd\u5bb6\u6807\u51c6\u5c40\u4e3aC\u8bed\u8a00\u5236\u5b9a\u4e86\u4e00\u5957\u5b8c\u6574\u7684\u7f8e\u56fd\u56fd\u5bb6\u6807\u51c6\u8bed\u6cd5\uff0c\u79f0\u4e3aANSI C\uff0c\u4f5c\u4e3aC\u8bed\u8a00\u6700\u521d\u7684\u6807\u51c6\u3002
\u76ee\u524d2011\u5e7412\u67088\u65e5\uff0c\u56fd\u9645\u6807\u51c6\u5316\u7ec4\u7ec7\uff08ISO\uff09\u548c\u56fd\u9645\u7535\u5de5\u59d4\u5458\u4f1a\uff08IEC\uff09\u53d1\u5e03\u7684C11\u6807\u51c6\u662fC\u8bed\u8a00\u7684\u7b2c\u4e09\u4e2a\u5b98\u65b9\u6807\u51c6\uff0c\u4e5f\u662fC\u8bed\u8a00\u7684\u6700\u65b0\u6807\u51c6\uff0c\u8be5\u6807\u51c6\u66f4\u597d\u7684\u652f\u6301\u4e86\u6c49\u5b57\u51fd\u6570\u540d\u548c\u6c49\u5b57\u6807\u8bc6\u7b26\uff0c\u4e00\u5b9a\u7a0b\u5ea6\u4e0a\u5b9e\u73b0\u4e86\u6c49\u5b57\u7f16\u7a0b\u3002
\u5176\u5b9e\u6838\u5fc3\u5c31\u662f\u5b9e\u73b0\u52a8\u6001\u6570\u7ec4\uff0c\u65e0\u8bba\u5b57\u7b26\u4e32\u591a\u957f\uff0c\u90fd\u80fd\u591f\u50a8\u5b58\u3002
\u7528getchar\u4e00\u4e2a\u4e00\u4e2a\u5f97\u5230\u5b57\u7b26\uff0c\u76f4\u5230\u6587\u4ef6\u7ed3\u675f\u3002
\u6838\u5fc3\u4ee3\u7801\u5b9e\u73b0\uff1a
int n=0,k=100; //\u521d\u59cb\u5316\uff0c\u5b57\u7b26\u4e32\u957f\u5ea6\u4e3a0\uff0c\u5b57\u7b26\u4e32\u7a7a\u95f4\u957f\u5ea6\u4e3a100 char * s2 = NULL,s1 = (char *)malloc(100); //\u521d\u59cb\u5316\u5b57\u7b26\u4e32\u7a7a\u95f4 if (s1 == NULL) return; //\u5185\u5b58\u5206\u914d\u5931\u8d25\uff0c\u8fd4\u56de while((c=getchar())!=EOF){ //\u5224\u65ad\u662f\u5426\u5230\u6587\u4ef6\u7ed3\u675f\uff0c\u4e00\u4e2a\u4e2a\u8bfb\u53d6\u5b57\u7b26 if(k<=n){ //\u5f53\u524d\u5b57\u7b26\u4e32\u957f\u5ea6\u5927\u4e8e\u7b49\u4e8e\u5b57\u7b26\u4e32\u7a7a\u95f4\u957f\u5ea6\u65f6 k*=2; //\u957f\u5ea6\u589e\u957f2\u500d s2 = (char *)realloc(s1,k); //\u91cd\u65b0\u5206\u914d\u5185\u5b58 if(s2 == NULL){ //\u5185\u5b58\u5206\u914d\u5931\u8d25 free(s1); //\u91ca\u653e\u5df2\u5206\u914d\u5185\u5b58 return; }else{ //\u5185\u5b58\u5206\u914d\u6210\u529f s1=s2; } } s1[n++]=c; //\u5b57\u7b26\u4e32\u8d4b\u503c\u5b57\u7b26 } s1[n]=0; //\u5b57\u7b26\u4e32\u672b\u5c3e\u7f6e\u4e3a\0
你要的随意大小字符串，刚出炉，还是热的。
#include <stdio.h>
#include<malloc.h>
#include<string.h>
#define maxsize 10
int main()
{
char *str,*strSave,cSave;
int i,n=2,strSize;
strSize=maxsize;
str=(char *)malloc(sizeof(char)*strSize);
printf("输入任意长度字符串：");
for(i=0;i<strSize;i++)
{
scanf("%c",&cSave);
if(i==strSize-1)//当输入到预设内存地址最后一位
{
if(cSave=='
')
{
cSave=0;
str[i]=cSave;
}
else
{
str[i]=0;
strSize=maxsize*n++;
strSave=str;
str=(char *)malloc(sizeof(char)*strSize);//当内存不够，增加1倍
strcpy(str,strSave);//新内存空间继承数据
str[i]=cSave;//保存新输入值
free(strSave);//释放旧内存空间
strSave=NULL;//防野指针
}
}
else
{
if(cSave=='
')
{
cSave=0;
str[i]=cSave;
break;
}
else
{
str[i]=cSave;
}
}
}
printf("打印输入的字符串为：%s",str);
return 0;
}
“随意大小”肯定是做不到的，即使软件平台不作限制，硬件资源也是有限的。正确的理解应当是使用者的主观感觉上没有上限限制。其于这种理解，下面提供的代码能做到这一点：
//#include "stdafx.h"//If the vc++6.0, with this line.
#include "stdio.h"
#include "string.h"
#include "stdlib.h"
char *mygets(char *p){
int N = sizeof(int)==4 ? 262144 : 32767;
char *q;
if((q=(char *)malloc(N))==NULL){//申请一个足够大的临时空间
printf("Application memory failure...
");
return NULL;
exit(0);
}
gets(q);
if((p=(char *)malloc(strlen(q)+1))==NULL){//按实际需要申请空间
printf("Failed to create a string...
");
return NULL;
exit(0);
}
strcpy(p,q);
free(q);//释放临时空间
return p;
}
int main(void){
char *str=NULL;
printf("Input a string...
");
if(!(str=mygets(str))) return 0;
printf("%s
",str);
free(str);
return 0;
}
c语言不能实现，字符串本质上还是字符数组以‘\0’字符结尾，在分配空间时必须指定数组长度，
例如：char str[]="abcdef";
C是不可能实现的
如果你要用C实现，至少要提供一个长度参数
绛旓細浣犺鐨闅忔剰澶у皬瀛楃涓诧紝鍒氬嚭鐐夛紝杩樻槸鐑殑銆俰nclude <stdio.h>#include<malloc.h>#include<string.h>#define maxsize 10int main(){ char *str,*strSave,cSave; int i,n=2,strSize; strSize=maxsize; str=(char *)malloc(sizeof(char)*strSize); printf("杈撳叆浠绘剰闀垮害瀛楃...
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