#include <stdio.h>

int add_range(int low, int high)

{

int i, sum;

for (i = low; i <= high; i++)

sum = sum + i;

return sum;

}

int main(void)

{

int result[100];

result[0] = add_range(1, 10);

result[1] = add_range(1, 100);

printf("result[0]=%d\nresult[1]=%d\n", result[0], result[1]);

return 0;

}

1 root@ubuntu:/opt/liuzw# gdb ./test  2 GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2.1) 7.4-2012.04  3 Copyright (C) 2012 Free Software Foundation, Inc.  4 License GPLv3+: GNU GPL version 3 or later 
      
         5 This is free software: you are free to change and redistribute it.  6 There is NO WARRANTY, to the extent permitted by law.  Type "show copying"  7 and "show warranty" for details.  8 This GDB was configured as "i686-linux-gnu".  9 For bug reporting instructions, please see: 10 
       ... 11 Reading symbols from /opt/liuzw/test...done. 12 (gdb) i locals                                 13 No frame selected.                         //没有变量 14 (gdb) n 15 The program is not being run.            //没有开始直接下一步是不对的 16 (gdb) start 17 Temporary breakpoint 1 at 0x8048415: file test.c, line 14. 18 Starting program: /opt/liuzw/test  19  20 Temporary breakpoint 1, main () at test.c:14 21 14        result[0] = add_range(1, 10);    //开始运行程序，经过定义变量，执行了第一条语句 22 (gdb) i locals                                 23 result = {-1208188928, 2, 134513196, -1207960576, -1207963660, -1207963660, -1209922512, 1, -1208104168, -1208058708, 0, 0, 0, 0, 0,  24   0, 0, -1208104168, 0, 0, 0, 3, -163754450, 1011, 0, -1209886408, -1207959944, -1207984804, -1209921992, 0, 38, -1209734771, 0, 0, 1,  25   2224, -1208104120, -1208104872, 134513228, -1209884328, 134513148, 1, -1209313744, -1209313186, -1073745400, -1207963660,  26   -1207960880, -1073745164, -1073745232, -1208058151, -1073745264, 134513148, -1073745288, -1207960972, 0, -1208104120, 1, 0, 1,  27   -1207961320, 0, 0, 0, -1208205324, -1073745298, -1073745297, 1, -1209312327, -1073745297, -1073745298, 0, -1208008724, -1073745164,  28   0, 0, -1209728909, 134513228, 0, 12648448, 1, -1073744675, 47, -1073745220, -1208205324, 134513776, 134520820, 1, 134513373,  29   -1208204316, 13, 134520820, 134513809, -1, -1209728570, -1208205324, -1209728427, -1208036736, 0, 134513785, -1208205324}    30                                                 //整形数组定义未初始化，内容为内存中随机值 31 (gdb) s     32 add_range (low=1, high=10) at test.c:6 33 6        for (i = low; i <= high; i++)     //带跳转函数的下一步命令：执行到第一条函数调用处，并执行了子函数经过变量定义后的第一条语句 34 (gdb) i locals  35 i = 0                                            //查看当前变量值，i因为被形参low赋值0所以为有效值，sum因为没有被初始化，值为内存中随机数 36 sum = -1208060323 37 (gdb) n     38 7            sum = sum + i;                //不跳转函数的下一步命令：执行了累计和函数 39 (gdb) i locals  40 i = 1                                            //经过累计和函数后，i变量执行到i++，所以增加1为1 41 sum = -1208060323                         //经过累计和函数后因为sum = -1208060323、i=0,累加赋值sum还是-1208060323 42 (gdb) n    43 6        for (i = low; i <= high; i++)    //不跳转函数的下一步命令，执行了for函数判断 44 (gdb) i locals   45 i = 1                                            //i由于被for一轮循环后的i++已经增为1 46 sum = -1208060322                        //sum经过+i，已经从-1208060323增大到-1208060322 47 (gdb) n                                         48 7            sum = sum + i; 49 (gdb) i locals 50 i = 2                                            //经过累计和函数后，i变量执行到i++，所以增加1为2 51 sum = -1208060322 52 (gdb) n 53 6        for (i = low; i <= high; i++) 54 (gdb) i locals  55 i = 2                                            //经过累计和函数后因为sum = -1208060322、i=2,累加赋值sum为-1208060320 56 sum = -1208060320 57 (gdb) n 58 7            sum = sum + i; 59 (gdb) i locals  60 i = 3                                            //经过累计和函数后，i变量执行到i++，所以增加1为3，因为还没有继续累加，保持sum = -1208060320 61 sum = -1208060320 62 (gdb) n 63 6        for (i = low; i <= high; i++) 64 (gdb) i locals  65 i = 3                                            //经过累计和函数后因为sum = -1208060320、i=3,累加赋值sum为-1208060317 66 sum = -1208060317 67 (gdb) n 68 7            sum = sum + i; 69 (gdb) i locals 70 i = 4 71 sum = -1208060317 72 (gdb) n 73 6        for (i = low; i <= high; i++) 74 (gdb) i locals 75 i = 4 76 sum = -1208060313 77 (gdb) n 78 7            sum = sum + i; 79 (gdb) i locals 80 i = 5 81 sum = -1208060313 82 (gdb) n 83 6        for (i = low; i <= high; i++) 84 (gdb) i locals 85 i = 5 86 sum = -1208060308 87 (gdb) n 88 7            sum = sum + i; 89 (gdb) i locals 90 i = 6 91 sum = -1208060308 92 (gdb) n 93 6        for (i = low; i <= high; i++) 94 (gdb) i locals 95 i = 6 96 sum = -1208060302 97 (gdb) n 98 7            sum = sum + i; 99 (gdb) i locals100 i = 7101 sum = -1208060302102 (gdb) n103 6        for (i = low; i <= high; i++)104 (gdb) i locals105 i = 7106 sum = -1208060295107 (gdb) n108 7            sum = sum + i;109 (gdb) i locals110 i = 8111 sum = -1208060295112 (gdb) n113 6        for (i = low; i <= high; i++)114 (gdb) i locals115 i = 8116 sum = -1208060287117 (gdb) n118 7            sum = sum + i;119 (gdb) i locals120 i = 9121 sum = -1208060287122 (gdb) n123 6        for (i = low; i <= high; i++)124 (gdb) i locals125 i = 9126 sum = -1208060278127 (gdb) n128 7            sum = sum + i;129 (gdb) i locals130 i = 10131 sum = -1208060278132 (gdb) n                                133 6        for (i = low; i <= high; i++)    //执行了for判断134 (gdb) i locals                        135 i = 10                                        //判断后达成，此时值sum继续累加10136 sum = -1208060268137 (gdb) n                                        138 8        return sum;                            //执行了子函数返回139 (gdb) i locals140 i = 11141 sum = -1208060268142 (gdb) n143 9    }144 (gdb) i locals145 i = 11146 sum = -1208060268147 (gdb) n                                //下一个函数调用处，此处整形数组为未初始化148 main () at test.c:15149 15        result[1] = add_range(1, 100);150 (gdb) i locals151 result = {-1208060268, 2, 134513196, -1207960576, -1207963660, -1207963660, -1209922512, 1, -1208104168, -1208058708, 0, 0, 0, 0, 0, 152   0, 0, -1208104168, 0, 0, 0, 3, -163754450, 1011, 0, -1209886408, -1207959944, -1207984804, -1209921992, 0, 38, -1209734771, 0, 0, 1, 153   2224, -1208104120, -1208104872, 134513228, -1209884328, 134513148, 1, -1209313744, -1209313186, -1073745400, -1207963660, 154   -1207960880, -1073745164, -1073745232, -1208058151, -1073745264, 134513148, -1073745288, -1207960972, 0, -1208104120, 1, 0, 1, 155   -1207961320, 0, 0, 0, -1208205324, -1073745298, -1073745297, 1, -1209312327, -1073745297, -1073745298, 0, -1208008724, -1073745164, 156   0, 0, -1209728909, 134513228, 0, 12648448, 1, -1073744675, 47, -1073745220, -1208205324, 134513776, 134520820, 1, 134513373, 157   -1208204316, 13, 134520820, 134513809, -1, -1209728570, -1208205324, -1209728427, -1208036736, 0, 134513785, -1208205324}158 (gdb) s159 add_range (low=1, high=100) at test.c:6160 6        for (i = low; i <= high; i++)161 (gdb) i locals162 i = 11163 sum = -1208060268164 (gdb) n165 7            sum = sum + i;166 (gdb) i locals167 i = 1168 sum = -1208060268169 (gdb) n170 6        for (i = low; i <= high; i++)171 (gdb) i locals172 i = 1173 sum = -1208060267174 (gdb) n175 7            sum = sum + i;176 (gdb) i locals177 i = 2178 sum = -1208060267179 (gdb) s180 6        for (i = low; i <= high; i++)181 (gdb) i locals182 i = 2183 sum = -1208060265184 (gdb) s185 7            sum = sum + i;186 (gdb) i locals187 i = 3188 sum = -1208060265189 (gdb) quit190