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Annotation of 43BSD/usr.lib/learn/C/L31.1a, revision 1.1

1.1     ! root        1: #print
        !             2: Write a function named "rev(s)" which reverses
        !             3: the string "s" in place. Name the file that contains
        !             4: the function "rev.c".
        !             5: When you're satisfied, type "ready".
        !             6: #once #create Ref
        !             7: cbax0987654321
        !             8: #once #create tzaqc.c
        !             9: main(){
        !            10:        char *s1, *s2, *s3, *s4;
        !            11:        s1 = "abc";
        !            12:        s2 = "x";
        !            13:        s3 = "";
        !            14:        s4 = "1234567890";
        !            15:        rev(s1);
        !            16:        rev(s2);
        !            17:        rev(s3);
        !            18:        rev(s4);
        !            19:        printf(s1);
        !            20:        printf(s2);
        !            21:        printf(s3);
        !            22:        printf(s4);
        !            23:        printf("\n");
        !            24: }
        !            25: #user
        !            26: cc tzaqc.c rev.o
        !            27: a.out >value
        !            28: #cmp value Ref
        !            29: #succeed
        !            30: /* One way:*/
        !            31: 
        !            32: rev (s)
        !            33: char *s;
        !            34: {
        !            35:        char *p;
        !            36:        int t;
        !            37:        
        !            38:        for (p=s; *p; p++)
        !            39:                ;
        !            40:        for (p--; p > s; p--, s++) {
        !            41:                t = *p;
        !            42:                *p = *s;
        !            43:                *s = t;
        !            44:        }
        !            45: }
        !            46: #log
        !            47: #next
        !            48: 32.1a 10

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