blocks|key|523351|text|不能(有效地)使用!=或==比较字符串，需要使用strcmp|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|523352|while+(strcmp(check,input)+!=+0)|code-block|syntax|javascript|523353|这是因为!=和==只会比较这些字符串的基地址。而不是字符串本身的内容。|523354|entityMap^0|9|2|C|2|O|6|0|0|4|2|7|2|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|N|$]]

You can't (usefully) compare strings using <code>!=</code> or <code>==</code>, you need to use <code>strcmp</code>:

<pre><code>while (strcmp(check,input) != 0)
</code></pre>

The reason for this is because <code>!=</code> and <code>==</code> will only compare the base addresses of those strings. Not the contents of the strings themselves.

blocks|key|739872|text|好的，有几件事：gets+is+unsafe和应该被替换为fgets(input,+sizeof(input),+stdin)，这样你就不会得到缓冲区溢出。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|739873|接下来，要比较字符串，必须使用strcmp，其中返回值0表示两个字符串匹配。使用相等运算符(即!=)比较两个字符串的地址，而不是它们内部的单个char。|739874|还要注意，虽然在本例中不会造成问题，但fgets也将换行符'\n'存储在缓冲区中；gets()则不会。如果将来自fgets()的用户输入与字符串文字(如"abc"+)进行比较，它将永远不会匹配(除非缓冲区太小，以至于'\n'无法放入其中)。|739875|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/q/1694036/15168^0|8|4|T|Y|8|E|0|0|F|6|1B|2|1Z|4|0|J|5|T|4|15|6|1K|7|24|5|30|4|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@$9|W|A|X|1|Y]]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|16|8|@$9|17|A|18|B|C]|$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

Ok a few things: <a href="https://stackoverflow.com/q/1694036/15168"><code>gets</code> is unsafe</a> and should be replaced with <code>fgets(input, sizeof(input), stdin)</code> so that you don't get a buffer overflow.

Next, to compare strings, you must use <code>strcmp</code>, where a return value of 0 indicates that the two strings match. Using the equality operators (ie. <code>!=</code>) compares the address of the two strings, as opposed to the individual <code>char</code>s inside them.

And also note that, while in this example it won't cause a problem, <code>fgets</code> stores the newline character, <code>'\n'</code> in the buffers also; <code>gets()</code> does not. If you compared the user input from <code>fgets()</code> to a string literal such as <code>"abc"</code> it would never match (unless the buffer was too small so that the <code>'\n'</code> wouldn't fit in it).

blocks|key|523505|text|您不能像这样直接比较数组|type|unstyled|depth|inlineStyleRanges|entityRanges|data|523506|array1==array2|code-block|syntax|javascript|523507|您应该逐个字符地比较它们；为此，您可以使用函数并返回一个布尔值(True:1，False:0)。然后，您可以在while循环的测试条件中使用它。|523508|试试这个：|523509|#include+<stdio.h>
int+checker(char+input[],char+check[]);
int+main()
{
++++char+input[40];
++++char+check[40];
++++int+i=0;
++++printf("Hello!\nPlease+enter+a+word+or+character:\n");
++++scanf("%25s",input);
++++printf("I+will+now+repeat+this+until+you+type+it+back+to+me.\n");
++++scanf("%25s",check);

++++while+(!checker(input,check))
++++{
++++++++printf("%25s\n",+input);
++++++++scanf("%25s",check);
++++}

++++printf("Good+bye!");

++++return+0;
}

int+checker(char+input[],char+check[])
{
++++int+i,result=1;
++++for(i=0;+input[i]!='\0'+%7C%7C+check[i]!='\0';+i%2B%2B)+{
++++++++if(input[i]+!=+check[i])+{
++++++++++++result=0;
++++++++++++break;
++++++++}
++++}
++++return+result;
}|523510|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You can't compare arrays directly like this

<pre><code>array1==array2
</code></pre>

You should compare them char-by-char; for this you can use a function and return a boolean (True:1, False:0) value. Then you can use it in the test condition of the while loop.

Try this:

<pre><code>#include &lt;stdio.h&gt;
int checker(char input[],char check[]);
int main()
{
 char input[40];
 char check[40];
 int i=0;
 printf("Hello!\nPlease enter a word or character:\n");
 scanf("%s",input);
 printf("I will now repeat this until you type it back to me.\n");
 scanf("%s",check);

 while (!checker(input,check))
 {
 printf("%s\n", input);
 scanf("%s",check);
 }

 printf("Good bye!");

 return 0;
}

int checker(char input[],char check[])
{
 int i,result=1;
 for(i=0; input[i]!='\0' || check[i]!='\0'; i++) {
 if(input[i] != check[i]) {
 result=0;
 break;
 }
 }
 return result;
}
</code></pre>

blocks|key|740079|text|使用strcmp。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|740080|这是在string.h库中，并且非常流行。如果字符串相等，则strcmp返回0。有关strcmp返回内容的更好解释，请参阅this。|740081|基本上，你要做的是：|740082|while+(strcmp(check,input)+!=+0)|code-block|syntax|javascript|740083|或|740084|while+(!strcmp(check,input))|740085|740086|while+(strcmp(check,input))|740087|你可以查看strcmp上的教程this。|740088|entityMap|0|LINK|mutability|MUTABLE|url|http://www.tutorialspoint.com/c_standard_library/c_function_strcmp.htm|1|https://stackoverflow.com/questions/34824838/what-does-strcmp-exactly-returns-in-c/34825545#34825545|2|http://www.programiz.com/c-programming/library-function/string.h/strcmp^0|2|6|2|6|0|0|3|8|U|6|16|6|1P|4|1|0|0|0|0|0|0|0|5|6|F|4|2|0^^$0|@$1|2|3|4|5|6|7|19|8|@$9|1A|A|1B|B|C]]|D|@$9|1C|A|1D|1|1E]]|E|$]]|$1|F|3|G|5|6|7|1F|8|@$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]]|D|@$9|1M|A|1N|1|1O]]|E|$]]|$1|H|3|I|5|6|7|1P|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|1Q|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1R|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1S|8|@]|D|@]|E|$M|N]]|$1|S|3|P|5|6|7|1T|8|@]|D|@]|E|$]]|$1|T|3|U|5|L|7|1U|8|@]|D|@]|E|$M|N]]|$1|V|3|W|5|6|7|1V|8|@$9|1W|A|1X|B|C]]|D|@$9|1Y|A|1Z|1|20]]|E|$]]|$1|X|3|-4|5|6|7|21|8|@]|D|@]|E|$]]]|Y|$Z|$5|10|11|12|E|$13|14]]|15|$5|10|11|12|E|$13|16]]|17|$5|10|11|12|E|$13|18]]]]

Use <a href="http://www.tutorialspoint.com/c_standard_library/c_function_strcmp.htm" rel="noreferrer"><code>strcmp</code></a>.

This is in <code>string.h</code> library, and is very popular. <code>strcmp</code> return 0 if the strings are equal. See <a href="https://stackoverflow.com/questions/34824838/what-does-strcmp-exactly-returns-in-c/34825545#34825545">this</a> for an better explanation of what <code>strcmp</code> returns.

Basically, you have to do:

<pre><code>while (strcmp(check,input) != 0)
</code></pre>

or

<pre><code>while (!strcmp(check,input))
</code></pre>

or 

<pre><code>while (strcmp(check,input))
</code></pre>

You can check <a href="http://www.programiz.com/c-programming/library-function/string.h/strcmp" rel="noreferrer">this</a>, a tutorial on <code>strcmp</code>.

blocks|key|740143|text|每当您尝试比较字符串时，请将它们与每个字符进行比较。为此，您可以使用名为strcmp(input1，input2)的内置字符串函数；您应该使用名为#include<string.h>的头文件|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|740144|尝试以下代码：|740145|#include<stdio.h>+
#include<stdlib.h>+
#include<string.h>++

int+main()+
{+
++++char+s[]="STACKOVERFLOW";
++++char+s1[200];
++++printf("Enter+the+string+to+be+checked\n");//enter+the+input+string
++++scanf("%25s",s1);
++++if(strcmp(s,s1)==0)//compare+both+the+strings++
++++{
++++++++printf("Both+the+Strings+match\n");+
++++}+
++++else
++++{
++++++++printf("Entered+String+does+not+match\n");++
++++}+
++++system("pause");++
}+|code-block|syntax|javascript|740146|entityMap^0|21|I|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

Whenever you are trying to compare the strings, compare them with respect to each character. For this you can use built in string function called strcmp(input1,input2); and you should use the header file called <code>#include&lt;string.h&gt;</code> 

Try this code:

<pre><code>#include&lt;stdio.h&gt; 
#include&lt;stdlib.h&gt; 
#include&lt;string.h&gt; 

int main() 
{ 
 char s[]="STACKOVERFLOW";
 char s1[200];
 printf("Enter the string to be checked\n");//enter the input string
 scanf("%s",s1);
 if(strcmp(s,s1)==0)//compare both the strings 
 {
 printf("Both the Strings match\n"); 
 } 
 else
 {
 printf("Entered String does not match\n"); 
 } 
 system("pause"); 
} 
</code></pre>

blocks|key|740208|text|++++#include<stdio.h>
++++#include<string.h>
++++int+main()
++++{
++++++++char+s1[50],s2[50];
++++++++printf("Enter+the+character+of+strings:+");
++++++++gets(s1);
++++++++printf("\nEnter+different+character+of+string+to+repeat:+\n");
++++++++while(strcmp(s1,s2))
++++++++{
++++++++++++printf("%25s\n",s1);
++++++++++++gets(s2);
++++++++}
++++++++return+0;
++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|740209|这是一个非常简单的解决方案，在这个解决方案中，您将获得您想要的输出。|unstyled|740210|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code> #include&lt;stdio.h&gt;
 #include&lt;string.h&gt;
 int main()
 {
 char s1[50],s2[50];
 printf("Enter the character of strings: ");
 gets(s1);
 printf("\nEnter different character of string to repeat: \n");
 while(strcmp(s1,s2))
 {
 printf("%s\n",s1);
 gets(s2);
 }
 return 0;
 }
</code></pre>

This is very simple solution in which you will get your output as you want.

blocks|key|523813|text|您需要使用strcmp()和#include+<string.h>|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|523814|!=和==运算符仅比较这些字符串的基地址。而不是字符串的内容|523815|while+(strcmp(check,+input))|code-block|syntax|javascript|523816|示例代码：|523817|#include+<stdio.h>
#include+<string.h>

int+main()
{
++++char+input[40];
++++char+check[40]+=+"end\n";+//dont+forget+to+check+for+\n

++++while+(+strcmp(check,+input)+)+//strcmp+returns+0+if+equal
++++{
++++++++printf("Please+enter+a+name:+\n");
++++++++fgets(input,+sizeof(input),+stdin);
++++++++printf("My+name+is:+%25s\n",+input);
++++}

++++printf("Good+bye!");
++++return+0;
}|523818|Note1：gets()不安全。请改用fgets()|523819|Note2:使用fgets()时，还需要检查'\n'换行符|523820|entityMap^0|5|8|E|J|0|0|2|3|2|0|0|0|0|6|6|J|7|0|8|7|M|4|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|16|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|17|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|18|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]]|D|@]|E|$]]|$1|S|3|T|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|V|$]]

You need to use <code>strcmp()</code> and you need to <code>#include &lt;string.h&gt;</code>
The <code>!=</code> and <code>==</code> operators only compare the base addresses of those strings. Not the contents of the strings
<pre><code>while (strcmp(check, input))
</code></pre>
Example code:
<pre><code>#include &lt;stdio.h&gt;
#include &lt;string.h&gt;

int main()
{
 char input[40];
 char check[40] = &quot;end\n&quot;; //dont forget to check for \n

 while ( strcmp(check, input) ) //strcmp returns 0 if equal
 {
 printf(&quot;Please enter a name: \n&quot;);
 fgets(input, sizeof(input), stdin);
 printf(&quot;My name is: %s\n&quot;, input);
 }

 printf(&quot;Good bye!&quot;);
 return 0;
}
</code></pre>
Note1: <code>gets()</code> is unsafe. Use <code>fgets()</code> instead
Note2: When using <code>fgets()</code> you need to check for <code>'\n'</code> new line charecter too

blocks|key|740319|text|您可以：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|740320|使用string.h中的strcmp()，它是更简单的版本|offset|length|style|CODE|740321|或者，如果你想使用你自己的，你可以使用类似这样的东西：|740322|int+strcmp(char+*s1,+char+*s2)
{
++++int+i;
++++while(s1[i]+!=+'\0'+&&+s2[i]+!=+'\0')
++++{
++++++++if(s1[i]+!=+s2[i])
++++++++{
++++++++++++return+1;
++++++++}
++++++++i%2B%2B;
++++}
++++return+0;
}|code-block|syntax|javascript|740323|我会这样使用strcmp()：|740324|while(strcmp(check,+input))
{
++++//+code+here
}|740325|entityMap^0|0|2|8|C|8|0|0|0|6|8|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@$D|W|E|X|F|G]|$D|Y|E|Z|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|10|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|11|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|12|8|@$D|13|E|14|F|G]]|9|@]|A|$]]|$1|Q|3|R|5|L|7|15|8|@]|9|@]|A|$M|N]]|$1|S|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|T|$]]

You can:
Use <code>strcmp()</code> from <code>string.h</code>, which is the easier version
Or if you want to roll your own, you can use something like this:
<pre><code>int strcmp(char *s1, char *s2)
{
 int i;
 while(s1[i] != '\0' &amp;&amp; s2[i] != '\0')
 {
 if(s1[i] != s2[i])
 {
 return 1;
 }
 i++;
 }
 return 0;
}
</code></pre>
I'd use <code>strcmp()</code> in a way like this:
<pre><code>while(strcmp(check, input))
{
 // code here
}
</code></pre>

I am trying to get a program to let a user enter a word or character, store it, and then print it until the user types it again, exiting the program. My code looks like this:
<pre><code>#include &lt;stdio.h&gt;

int main()
{
 char input[40];
 char check[40];
 int i=0;
 printf(&quot;Hello!\nPlease enter a word or character:\n&quot;);
 gets(input); /* obsolete function: do not use!! */
 printf(&quot;I will now repeat this until you type it back to me.\n&quot;);

 while (check != input)
 {
 printf(&quot;%s\n&quot;, input);
 gets(check); /* obsolete function: do not use!! */
 }

 printf(&quot;Good bye!&quot;);
 

 return 0;
}
</code></pre>
The problem is that I keep getting the printing of the input string, even when the input by the user (check) matches the original (input). Am I comparing the two incorrectly?

How do I properly compare strings in C?

我正在尝试让一个程序让用户输入一个单词或字符，存储它，然后打印它，直到用户再次键入它，退出程序。我的代码如下所示：#include <stdio.h>int main(){ char input[40]; char check[40]; int i=0; printf("Hello!\nPlea...

问如何正确地比较C中的字符串？
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